fbpx
Wikipedia

Enobosarm

January 01, 1970

"Ostarine" redirects here. For the chemical structure mistakenly linked to the name, see Andarine.

Enobosarm, also formerly known as ostarine and by the developmental code names GTx-024, MK-2866, and S-22, is a selective androgen receptor modulator (SARM) which is under development for the treatment of androgen receptor-positive breast cancer in women and for improvement of body composition (e.g., prevention of muscle loss) in people taking GLP-1 receptor agonists like semaglutide.[1][5][7][8][9] It was also under development for a variety of other indications, including treatment of cachexia, Duchenne muscular dystrophy, muscle atrophy or sarcopenia, and stress urinary incontinence, but development for all other uses has been discontinued.[1][10][2] Enobosarm was evaluated for the treatment of muscle wasting related to cancer in late-stage clinical trials, and the drug improved lean body mass in these trials, but it was not effective in improving muscle strength.[11][2][12][10][13] As a result, enobosarm was not approved and development for this use was terminated.[2] Enobosarm is taken by mouth.[2]

Enobosarm
Clinical data
Other namesOstarine; GTx-024; MK-2866; S-22; VERU-024[1]
Routes of
administration		By mouth[2]
ATC code
  • None
Legal status
Legal status
Pharmacokinetic data
Bioavailability100% (rats)[3]
MetabolismCYP3A4, UGT1A1, UGT2B7[4]
MetabolitesEnobosarm glucuronide[4]
Elimination half-life14–24 hours[5][6][4][7]
ExcretionFeces (70%), urine (21–25%) (rats)[3]
Identifiers
  • ((2S)-3-(4-cyanophenoxy)-N-[4-cyano-3-(trifluoromethyl)phenyl]-2-hydroxy-2-methylpropanamide)
CAS Number
  • 841205-47-8
PubChem CID
  • 11326715
DrugBank
  • DB12078 Y
ChemSpider
  • 9501667
UNII
  • O3571H3R8N
KEGG
  • D10221
ChEMBL
  • ChEMBL1738889
PDB ligand
  • RLJ (PDBe, RCSB PDB)
CompTox Dashboard (EPA)
  • DTXSID30233006
Chemical and physical data
FormulaC19H14F3N3O3
Molar mass389.334 g·mol−1
3D model (JSmol)
  • Interactive image
Melting point132 to 136 °C (270 to 277 °F)
  • O=C(NC1=CC=C(C#N)C(C(F)(F)F)=C1)[C@](C)(O)COC2=CC=C(C#N)C=C2
  • InChI=1S/C19H14F3N3O3/c1-18(27,11-28-15-6-2-12(9-23)3-7-15)17(26)25-14-5-4-13(10-24)16(8-14)19(20,21)22/h2-8,27H,11H2,1H3,(H,25,26)/t18-/m0/s1
  • Key:JNGVJMBLXIUVRD-SFHVURJKSA-N
  (verify)

Known possible side effects of enobosarm include headache, fatigue, anemia, nausea, diarrhea, back pain, adverse lipid changes like decreased high-density lipoprotein (HDL) cholesterol levels, changes in sex hormone concentrations like decreased testosterone levels, elevated liver enzymes, and liver toxicity, among others.[6][14][15][16][12] The potential masculinizing effects of enobosarm, for instance in women, have largely not been evaluated and are unknown.[17] The potential adverse effects and risks of high doses of enobosarm are also unknown.[17] Enobosarm is a nonsteroidal SARM, acting as an agonist of the androgen receptor (AR), the biological target of androgens and anabolic steroids like testosterone and dihydrotestosterone (DHT).[10] However, it shows dissociation of effect between tissues in preclinical studies, with agonistic and anabolic effects in muscle and bone, agonistic effects in breast, and partially agonistic or antagonistic effects in the prostate gland and seminal vesicles.[7][10][2][18][19] The AR-mediated effects of enobosarm in many other androgen-sensitive tissues are unknown.[18][20]

Enobosarm was first identified in 2004[11] and has been under clinical development since at least 2005.[1][18] It is the most well-studied SARM of all of the agents that have been developed.[21] According to GTx, its developer, a total of 25 clinical studies have been carried out on more than 1,700 people involving doses from 1 to 100 mg as of 2020.[10][22] However, enobosarm has not yet completed clinical development or been approved for any use.[1][2] As of November 2023, it is in phase 3 clinical trials for the treatment of breast cancer and is in phase 2 studies for improvement of body composition in people taking GLP-1 receptor agonists.[1][9] Enobosarm was developed by GTx, Inc., and is now being developed by Veru, Inc.[1]

Aside from its development as a potential pharmaceutical drug, enobosarm is on the World Anti-Doping Agency list of prohibited substances and is sold for physique- and performance-enhancing purposes by black-market Internet suppliers.[10][17] In one survey, 2.7% of young male gym users reporting using SARMs.[23] In addition, a London wastewater analysis found that enobosarm was the most abundant "pharmaceutical drug" detected and was more prevalent than recreational drugs like MDMA and cocaine.[24] Enobosarm is often used in these contexts at doses greatly exceeding those evaluated in clinical trials, with unknown effectiveness and safety.[17] Many products sold online that are purported to be enobosarm either contain none or contain other unrelated substances.[17][25] Social media has played an important role in facilitating the widespread non-medical use of SARMs.[26]

Medical uses edit

Enobosarm is not approved for any medical use and is not available as a licensed pharmaceutical drug as of 2023.[1][2][10][17]

Side effects edit

General side effects that have been reported with enobosarm in clinical trials include headache, fatigue, anemia, nausea, diarrhea, and back pain.[6][27][14]

Enobosarm has shown dose-related adverse effects on serum lipids, sex hormone and gonadotropin levels, and carrier protein levels in clinical trials.[16][17][28] It decreases HDL cholesterol levels, reducing them dose-dependently by 17% at a dose of 1 mg/day and by 27% at a dose of 3 mg/day.[16][17][28] Decreases in total cholesterol levels and in triglyceride levels have also been seen, whereas LDL cholesterol levels are unchanged.[16][17][28] In healthy elderly men, total testosterone levels decreased significantly at doses of 1 and 3 mg/day (-31% and -57%, respectively), whereas levels of free testosterone, dihydrotestosterone (DHT), estradiol, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) did not change significantly at doses up to 3 mg/day.[16][28] In healthy postmenopausal women, LH and FSH decreased significantly only at the 3 mg/day dose (-17% and -30%, respectively), whereas levels of total testosterone, free testosterone, DHT, and estradiol did not clearly change relative to placebo.[16][17][28] SHBG levels were lowered at doses of 1 to 3 mg/day, decreasing dramatically by 61% in men and by 80% in women at the 3 mg/day dose.[16][17][28] For comparison, testosterone enanthate by intramuscular injection at a highly supraphysiological dose of 600 mg/week resulted in only a 31% decrease in SHBG levels.[28][29] Despite the large changes in SHBG levels, levels of free testosterone did not significantly change in either men or women.[16][17][28] Small but significant increases in hemoglobin and hematocrit, and small but significant decreases in fasting blood glucose, insulin levels, and insulin resistance, have been observed with enobosarm at 3 mg/day.[17][30][28][6]

In small short-term (3-month) clinical trials in healthy elderly or postmenopausal women, enobosarm at doses ranging from 0.1 to 3 mg/day had mixed effects on sebum production and did not increase body hair growth or cause hirsutism.[31][28] These effects are measures of androgenic action in skin and hair follicles.[31] In the first study, at doses of 0.1 to 3 mg/day, there were no significant changes relative to placebo in sebum tape scores with enobosarm and there were no consistent increases in Ferriman–Gallwey score, with most women having no change in score or a decreased score and only one having an increase in score.[31][28] In the second study, which employed 3 mg/day enobosarm, there was a significant 1.25-fold increase in sebum production from baseline and a significant 1.5-fold increase in sebum production relative to placebo.[31] No differences in sebaceous gland volume were apparent upon histological examination in this study.[31]

At doses ranging from 0.1 to 18 mg/day in clinical trials, enobosarm has been associated with elevated liver enzymes in subsets of individuals.[12][16] Rates of elevated liver enzymes or of elevated alanine aminotransferase (ALT) levels have ranged from 0.6% to 33% in these trials.[12][16] Liver enzyme elevations with enobosarm are often transient and resolve spontaneously.[12] However, markedly elevated liver enzymes have occasionally occurred with enobosarm in clinical trials and have necessitated discontinuation.[12] There have been several published case reports of hepatotoxicity with enobosarm as of 2023.[12][32][23][33][34][35][36] Between 2020 and 2022, there has been a rapid increase in reported cases of liver toxicity with SARMs.[32] The hepatotoxicity with SARMs may be related to their resistance to hepatic metabolism, analogously to the case of 17α-alkylated anabolic steroids.[12]

SARMs are often advertised and sold on the Internet at doses higher than have been described in the literature.[17][27] Sometimes doses are recommended as several-fold or more greater than the doses used in clinical trials, or seemingly arbitrary doses are advised.[17][27] For instance, enobosarm has been provided at doses of greater than or equal to 20 mg per serving and recommended by bodybuilders and fitness enthusiasts at doses of 10 to 30 mg/day, relative to the most widely assessed highest dose in clinical trials of 3 mg/day—an up to 10-fold difference.[17][27] SARMs, particularly when used at high or excessive doses for prolonged periods of time, may result in substantial suppression of endogenous sex hormones like testosterone and estradiol, in turn producing widespread unintended deleterious effects on physiological function.[17] As examples, SARMs may produce potent anabolic effects with deficiency in important androgenic effects, may result in estrogen deficiency with consequences like bone loss among others, and, due to suppression of the hypothalamic–pituitary–gonadal axis (HPG axis), may cause infertility.[17]

Androgens and anabolic steroids like testosterone, dihydrotestosterone (DHT), nandrolone, and oxandrolone, which are full agonists of the androgen receptor, produce virilizing or masculinizing effects like increased sebum production and acne, increased body hair growth, scalp hair loss, voice deepening, increased muscle mass, android fat redistribution, skeletal changes like widening of the shoulders and skull/facial changes, and genital growth both in males and females.[37][38][17] SARMs, which are tissue-selective mixed or partial agonists of the androgen receptor, are largely uncharacterized in terms of their masculinizing effects, but are likely to produce many of the same effects.[17][37][39][40] SARMs specifically may be expected to retain masculinizing effects like increased muscle mass and bone changes, while possibly having reduced virilizing effects in certain other areas like androgenic skin and hair changes.[17][16][31][18][20] Anecdotal reports of masculinization with SARMs in women exist in online forums.[26]

The United States Food and Drug Administration (FDA) has cautioned that SARMs could have serious adverse effects ranging from risk of heart attack to stroke and liver damage and has warned against their use in bodybuilding products.[41]

Overdose edit

Enobosarm has been assessed in clinical trials at doses ranging from 0.1 to 18 mg/day.[10] However, most research has been done at doses of 0.1 to 3 mg/day, with two phase 3 clinical trials using a dosage of 3 mg/day.[2][15][32][17] A few small phase 1 and phase 2 trials of enobosarm for breast cancer have employed doses of 9 to 18 mg/day.[42][12][2][43] Larger, phase 3 trials of enobosarm at a dose of 9 mg/day for breast cancer (e.g., ARTEST, n=210) are now underway.[44][45] Doses of up to 100 mg have been assessed in single-dose pharmacokinetic studies and doses of up to 30 mg/day have been given in short 14-day pharmacokinetic studies.[5] Enobosarm sold via black-market Internet suppliers and used non-medically is often taken at much higher doses than those used widely in clinical trials (e.g., 10–30 mg/day), with unknown adverse effects and risks.[17][27]

Interactions edit

Enobosarm is a substrate of the cytochrome P450 enzyme CYP3A4 and the UDP-glucuronosyltransferase (UGT) enzymes UGT1A1 and UGT2B7.[4] It shows very minimal metabolism by cytochrome P50 enzymes, with CYP3A4 merely responsible for the greatest degree of metabolism.[4] Since enobosarm is metabolized by CYP3A4, UGT1A1, and UGT2B7, inhibitors and inducers of these enzymes can modify the metabolism and pharmacokinetics of enobosarm.[4] The strong CYP3A4 inhibitor itraconazole was shown to have minimal to no influence on the pharmacokinetics of enobosarm, whereas the strong CYP3A4 inducer rifampin reduced enobosarm peak levels by 23%, elimination half-life by 23%, and area-under-the-curve levels by 43%.[46][4] The pan-UGT inhibitor probenecid was shown to not affect peak levels of enobosarm but to increase the elimination half-life of enobosarm by 78% and to increase area-under-the-curve levels of enobosarm by 50%.[46][4] Enobosarm had no effect on the pharmacokinetics of celecoxib (a CYP2C9 substrate) or rosuvastatin (a BCRP substrate).[4] Based on the preceding findings, it was concluded that enobosarm poses low risk for clinically relevant drug interactions.[4]

Pharmacology edit

Pharmacodynamics edit

Enobosarm is a selective androgen receptor modulator (SARM), or a tissue-selective mixed agonist or partial agonist of the androgen receptor (AR).[20][11][18] This receptor is the biological target of endogenous androgens like testosterone and dihydrotestosterone (DHT) and of synthetic anabolic steroids like nandrolone and oxandrolone.[11][18][37] The affinity (Ki) of enobosarm for the AR is high and was measured as 3.8 nM in one study, or approximately 16.8% of that of DHT.[47][48][49] Enobosarm shows enantioselectivity for the AR and has similar but somewhat lower potency than DHT in terms of activating the receptor.[7] In addition to general activation of the AR, enobosarm induces the N/C interaction (the interaction of the amino terminus and carboxyl terminus) of the AR less potently than does DHT, but in any case promotes the N/C interaction concentration-dependently and to the same maximal extent as DHT.[49] The AR is widely expressed in tissues throughout the body, including in the prostate gland, seminal vesicles, genitals, gonads, skin, hair follicles, muscle, bone, heart, adrenal cortex, liver, kidneys, and brain, among others.[18][37] The effects of SARMs including enobosarm in many of these tissues have yet to be characterized.[18][20] In any case, enobosarm has been demonstrated to have varying full agonist or partial agonist or antagonist actions in specific tissues, including potent agonistic and anabolic effects in muscle and bone, potent agonistic effects in AR-expressing human breast cancer cell lines like MCF-7 and MDA-MB-231,[19][2] and partially agonistic or antagonistic effects in the prostate gland, seminal vesicles, and uterus.[7][10][2][18][49] Enobosarm has additionally been shown to stimulate sexual motivation in female rats similarly to testosterone.[47][49] Although enobosarm has not been specifically assessed in this area, another structurally unrelated quinolinone SARM, LGD-2226, has shown prosexual effects in male rats comparable to those of the synthetic androgen and anabolic steroid fluoxymesterone as well.[2][47][50]

The molecular mechanisms underlying the tissue-selective effects of enobosarm and other SARMs compared to testosterone and other androgens and anabolic steroids remain unknown.[51][17] However, recruitment of both coactivators and corepressors instead of only coactivators and resultant differing receptor conformations, distinct tissue-specific modulation of signaling pathways mediating genomic and non-genomic effects, and differences in within-tissue ligand metabolism and modulation of ligand potency (i.e., potentiation versus lack thereof), among others, all constitute possible mechanisms.[51][17][52] In terms of coregulator recruitment, the ratios of coactivators to corepressors vary in different tissues throughout the body, and it is thought that SARMs may have agonistic effects in tissues with an excess of coactivators relative to corepressors like muscle and bone and may have partially agonistic or antagonistic effects in tissues with an excess of corepressors over coactivators like the prostate.[51] Another mechanism may be that SARMs like enobosarm induce the N/C interaction less readily than AR full agonists like DHT.[17][47][53][49] Induction of the N/C interaction has been associated with the effects of endogenous and exogenous AR agonists, for instance virilization and prostate growth.[47][49][54][55]

In animal studies, enobosarm has shown potent muscle-promoting effects that were similar to those of testosterone and DHT.[7][10][56][57][58][48] In one of the first published studies, enobosarm maximally restored prostate weight to 51%, seminal vesicle weight to 98%, and levator ani muscle weight to 136% in castrated male rats relative to gonadally intact control male rats, with an ED50 dose for muscle of 0.03 mg/day.[56][51][48] For comparison, testosterone propionate was able to maximally stimulate levator ani muscle to 104% and prostate weight to 121%, with ED50 doses of 0.15 mg/day and 0.13 mg/day, respectively.[7] Hence, enobosarm was able to stimulate the levator ani muscle to a size greater than that in normal male rats or produced with exogenous testosterone in castrated male rats, but was only capable of partially rescuing prostate gland weight.[51][48][7] Additionally, enobosarm fully maintained or restored levator ani weight at doses that did not affect LH or FSH levels in gonadally intact animals (≤0.1 mg/day).[7] As such, it was more potent in stimulating muscle than testosterone at doses that did not affect gonadotropin levels.[5][7] In gonadally intact male rats, enobosarm significantly increased levator ani muscle weight to 131% of intact controls but significantly decreased the weights of the prostate gland and seminal vesicles, demonstrating an antagonistic or partially agonistic effect in these tissues.[7] In another animal study, enobosarm and DHT increased levator ani weights to similar or slightly different extents in intact male rats, but DHT strongly increased prostate weight while enobosarm reduced prostate weight.[7][59][58] Aside from effects in muscle tissue, enobosarm has been assessed and found to completely maintain bone quality and composition in castrated male rats and to partially but not fully prevent bone loss in ovariectomized female rats, indicating potent anabolic effects in bone as well.[7]

In a phase 2 human clinical trial in healthy elderly men and postmenopausal women, enobosarm dose-dependently increased lean body mass (muscle mass) across doses of 0.1, 0.3, 1, and 3 mg/day, with a significant 1.3 kg gain over placebo at 3 mg/day and a non-significant 0.7 kg gain over placebo at 1 mg/day.[10][28] Similarly, in two phase 3 clinical trials in men and postmenopausal women with muscle wasting due to non-small-cell lung cancer, enobosarm at 3 mg/day significantly increased lean body mass by 0.41 kg and 0.47 kg.[10] However, enobosarm did not successfully increase muscle strength in these phase 3 trials.[10] In any case, it has been suggested that the study designs and physical function outcomes in such trials may have been flawed.[60][61][62][63][2] The increases in lean body mass that have been seen with employed doses of enobosarm in clinical trials are very modest compared to those produced with supraphysiological doses of testosterone over similar timeframes (e.g., 0.5–1.5 kg with enobosarm versus 5–8 kg with 300–600 mg/week intramuscular testosterone enanthate in healthy young men).[53][17][64] The effects of higher doses of enobosarm (9–18 mg/day) on lean body mass and muscle strength are also being evaluated in women with breast cancer.[2][43] There is some evidence that women may be more sensitive to lean body mass increases with SARMs, specifically GSK-2881078 but potentially also others like enobosarm, than men.[10][17]

In addition to its mixed agonist–antagonist activity at the AR, enobosarm is likely to also differ from steroidal androgens in its effects due to differences in within-tissue ligand metabolism.[37][31][18][52] The virilizing and androgenic effects of the traditional steroidal androgens like testosterone in skin, hair follicles, and the prostate gland are attributed to high expression of 5α-reductase in these tissues and consequent local conversion and potentiation into more potent androgens.[37][31][18] In the case of testosterone, this is via conversion into the 10-fold more potent androgen DHT.[31][18] Enobosarm is not subject to this local transformation and potentiation, and so is theorized to have greatly reduced effects in these tissues relative to testosterone and certain other steroidal androgens.[31][18][20] This is likewise theorized to be the case for non-5α-reductase-potentiated anabolic steroids like nandrolone and oxandrolone, which have high myotrophic–androgenic potency ratios in animals.[37] The lack of 5α-reduction may result in reduced androgenic side effects like scalp hair loss, facial and body hair growth, and prostate growth.[20][65][11] On the other hand, although SARMs, like enobosarm, as well as anabolic steroids, may have reduced virilizing effects in skin and hair follicles, this is not necessarily the case for virilization in general.[37][17] In particular, the muscle-promoting effects of these agents can be considered a masculinizing effect.[16][66] The potential masculinizing effects of enobosarm and SARMs in general are largely uncharacterized and unknown.[17] Aside from metabolism differences related to 5α-reduction, enobosarm has also shown much greater impact in the liver, specifically on certain aspects of hepatic protein synthesis like reduction of sex hormone-binding globulin (SHBG) production, than even highly supraphysiological doses of parenteral testosterone.[28] This phenomenon has also been seen with other SARMs, such as LGD-4033,[17][32][16][67] as well as with synthetic orally active 17α-alkylated anabolic steroids like stanozolol.[20][68][69] It can be attributed to the first pass through the liver with oral administration and to the high oral bioavailability and strong resistance to hepatic metabolism of these agents.[20][70][71][12]

Enobosarm has no estrogenic activity, either intrinsic to itself or via its metabolites.[31][7][18][20][42] As a result, the drug is not expected to have feminizing effects or risk of gynecomastia (breast development) nor to stimulate estrogen-sensitive breast cancer.[18][7] SARMs like enobosarm are not ideal agents for androgen replacement therapy as they are not expected to reproduce the full spectrum of effects of testosterone and other androgens, including not only AR-mediated effects but also notably aromatization into estrogen and required physiological estrogenic effects in bone and brain.[20] Enobosarm has been found to be a weak antagonist of the progesterone receptor and hence might have some capacity for antiprogestogenic effects.[5][7] Aside from its weak interaction with the progesterone receptor, enobosarm is highly selective for the AR and does not bind to other nuclear hormone receptors.[7]

Pharmacokinetics edit

Absorption edit

Enobosarm is orally bioavailable due to a lack of extensive first-pass metabolism.[18] In rats, the oral bioavailability of enobosarm was found to be 100%.[3] Enobosarm is rapidly absorbed with oral administration and reaches maximal concentrations median 1.0 hours (range 1.0–2.0 hours) following administration.[46][5][4] The drug reaches a peak concentration of 56.0 ng/mL (range 53.1–123.0 ng/mL) following a single 3 mg dose and a steady-state peak of 68.1 ng/mL following repeated 3 mg doses.[46][4] The pharmacokinetics of enobosarm are linear and proportional over a dose range of 1 to 100 mg in single doses in healthy men.[5][7] The pharmacokinetics of enobosarm are similar in young versus elderly individuals.[7] A concentration–time curve of enobosarm levels following a single oral dose of enobosarm in humans has been published.[7]

Distribution edit

Enobosarm is a small-molecule and highly lipophilic compound.[72][73] Compounds of this type are typically able to diffuse freely through biological membranes such as cell membranes and barriers like the blood–brain barrier.[74][75] This is in fact essential for the action of nuclear receptor ligands like enobosarm since their biological targets (the androgen receptor in this case) are located intracellularly.[74][75] One in silico study predicted that, on the basis of its overall physicochemical properties (but not considering active transport), enobosarm would be unlikely to cross the blood–brain barrier and hence would be a peripherally selective drug with reduced or no central nervous system effects.[76] However, in a rat tissue distribution study, enobosarm was found to be concentrated in brain tissues to a similar extent as other target tissues like skeletal muscle, bone, prostate, and seminal vesicles.[3] This is consistent with enobosarm producing centrally mediated effects in humans like suppression of LH and FSH secretion.[16][17][28]

Enobosarm does not bind to sex hormone-binding globulin.[18]

Metabolism edit

In vitro studies found very minimal metabolism of enobosarm by human cytochrome P450 enzymes.[4] The greatest degree of oxidative metabolite generation occurred with CYP3A4.[4] Upon incubation with human UDP-glucuronosyltransferase (UGT) enzymes, enobosarm glucuronide was generated, with a majority of this inactive metabolite being produced by UGT1A1 and UGT2B7.[4] Enobosarm glucuronide is the primary circulating metabolite of enobosarm.[4]

Coadministration of the strong CYP3A4 inhibitor itraconazole had minimal impact on the pharmacokinetics of enobosarm and enobosarm glucuronide, whereas the strong CYP3A4 inducer rifampin reduced enobosarm peak levels by 23%, elimination half-life by 23%, and area-under-the-curve levels by 43%.[46][4] Coadministration of the pan-UGT inhibitor probenecid with enobosarm resulted in similar peak levels of enobosarm but the elimination half-life of enobosarm was extended by 78% and area-under-the-curve levels increased by 50%.[46][4] These data are consistent with the preclinical findings that enobosarm is a substrate of CYP3A4 and UGT enzymes.[4]

The metabolism of enobosarm is similar to that of the closely structurally related drug bicalutamide.[3]

Elimination edit

In rats, enobosarm was excreted approximately 70% in feces and 21 to 25% in urine.[3]

Enobosarm has an elimination half-life of approximately 14 to 24 hours in human volunteers.[5][6][7] In one pharmacokinetic study, the mean terminal half-life was 22.0 ± 5.8 (SD) hours, with a range of 13.7 to 31.3 hours in different individuals[4]

Chemistry edit

Enobosarm is a small-molecule (molecular weight = 389.3 g/mol) and highly lipophilic (predicted log P = 2.7–3.3) compound.[72][73]

Enobosarm and related SARMs like acetothiolutamide and andarine (acetamidoxolutamide; GTx-007; S-4) were derived from structural modification of the arylpropionamide nonsteroidal antiandrogen bicalutamide.[77][18][78][20][79] They are nonsteroidal arylpropionamides themselves and are close structural analogues of bicalutamide.[18][78][79][80] Bicalutamide was used to derive acetothiolutamide, andarine was developed from acetothiolutamide, the SARM S-1 was developed from andarine, and finally enobosarm was developed from S-1.[81] Bicalutamide is used clinically as an antiandrogen, but there is some evidence that bicalutamide itself may have some SARM-like properties in certain tissues, for instance in muscle and bone.[82][83][84]

Enobosarm (S-22) and andarine (S-4) and their chemical structures have sometimes been confused.[85] The chemical structure of enobosarm was not disclosed until November 2011.[47][85]

Novel nonsteroidal antiandrogens have been developed from enobosarm with enhanced potency and activity relative to conventional antiandrogens like bicalutamide and enzalutamide.[86][87]

History edit

The first SARMs were arylpropionamides derived from the nonsteroidal antiandrogen bicalutamide.[7][88] They were discovered by James T. Dalton and colleagues at the University of Tennessee and other institutions and were first described in a paper published in 1998.[7][88][89] At the time, these AR agonists were referred to as "nonsteroidal androgens", a drug class that had not been previously described.[90] By 1999 however, on the basis of the selective estrogen receptor modulator (SERM)-like mixed agonist–antagonist and tissue-selective activity of these nonsteroidal AR agonists, the term "selective androgen receptor modulator" or "SARM" was introduced and adoption of this name had begun.[90] The arylpropionamide SARM andarine (GTx-007; S-4) was first described in the literature by 2002.[91][92][93] In 2003, arylpropionamide AR agonists, including andarine, were first reported to possess SARM-type tissue selectivity in vivo.[47][92] Enobosarm (GTx-024; S-22), another arylpropionamide SARM, was first identified in 2004[11][89] and was first described in the literature in 2005.[18][48][89] GTx, a pharmaceutical company founded in Memphis, Tennessee in 1997, licensed the rights to enobosarm from the University of Tennessee Research Foundation and began developing it as a pharmaceutical drug.[1][89]

A phase 1 clinical trial employing enobosarm had been completed by 2005.[18] By 2007, enobosarm was in a phase 2 trial, and that year GTx signed an exclusive license agreement for its SARM program with Merck & Co.[94] The companies ended the deal in 2010.[95] In August 2011, there was a 12-week double-blind, placebo controlled phase 2 trial that focused on elderly men and postmenopausal women which concluded that enobosarm showed statistically significant improvements in total lean body mass and physical function without apparent adverse effects on hair growth or sebum production.[28] In August 2013, GTx announced that enobosarm had failed in two phase 3 clinical trials to treat wasting in people with lung cancer.[96] The company had invested around $35 million in the development of the drug.[97] The company said at that time that it planned to pursue approval of enobosarm in Europe; the company was also still developing GTx-758, a nonsteroidal estrogen, for castration-resistant prostate cancer.[98] As of 2018, enobosarm was the only SARM to have reached or completed phase 3 clinical trials.[51]

In 2016, GTx began phase 2 trials, to see if enobosarm might be effective to treat stress urinary incontinence in women.[99] In 2018, GTx announced the phase 2 trials on the effectiveness of enobosarm for stress urinary incontinence in women failed to achieve its primary endpoint in the ASTRID Trial.[100] By September 2023, development of enobosarm for stress urinary incontinence had been discontinued.[1] In 2022, the FDA granted fast tract designation to enobosarm in AR+, ER+, HER2- metastatic breast cancer.[101] In January 2024, Veru Inc. submitted an Investigational New Drug application to the FDA of enobosarm for prevention of muscle loss and augmentation of fat loss in combination with glucagon-like peptide-1 (GLP-1) receptor agonists like semaglutide for weight loss.[9] In addition, they announced plans to conduct a phase 2b study of enobosarm at doses of 3 to 6 mg/day for this purpose in sarcopenic obese or overweight elderly individuals receiving GLP-1 receptor agonists.[9]

Enobosarm was developed by GTx, Inc., and is now being developed by Veru, Inc.[1]

Society and culture edit

Names edit

Enobosarm is the generic name of the drug and its International Nonproprietary Name (INN).[102] Ostarine was a tentative brand name of the drug created by GTx, Inc. that did not end up being used for marketing purposes but continues to be used as a synonym for the drug.[1][6] Enobosarm is also known by the pharmaceutical developmental code names S-22 (synthesis paper), GTx-024 (GTx, Inc.), MK-2866 (Merck), and VERU-024 (Veru, Inc.).[1]

Non-medical use edit

Enobosarm and other SARMs are sold by black-market vendors on the Internet.[17][25] These agents have increasingly become used by the general public as "gym supplements" such as pre-workout or lifestyle drugs, rather than as an aid to performance in athletic or bodybuilding competitions. In one survey, 2.7% of young male gym users in the Netherlands reporting using SARMs.[23] In addition, a 2018 analysis of a fatberg from a sewer in central London showed enobosarm to be the most abundant "pharmaceutical drug" detected, and was present at higher concentration than recreational drugs such as MDMA and cocaine. While this isolated result may not be representative of overall levels of use, for enobosarm to be detectable in sewer deposits reflects significant levels of enobosarm use in the area close to where the sample was collected.[24] Doses of enobosarm sold online and used non-medically are often many times higher than those assessed in clinical trials.[17][27] Aside from enobosarm, the other most commonly used SARMs include vosilasarm (RAD140; "testolone"), LGD-4033 (VK5211; "ligandrol"), and andarine (GTx-007; S-4).[26] Many products sold online that are purported to be enobosarm either contain none or contain other unrelated substances, and doses are also frequently not as labeled.[17][25] Social media has played an important role in facilitating the widespread non-medical use of SARMs.[26]

Doping in sport edit

SARMs including enobosarm may be and have been used by athletes to assist in training and increase physical stamina and fitness, potentially producing effects similar to anabolic steroids. For this reason, SARMs were banned by the World Anti-Doping Agency in January 2008, despite no drugs from this class yet being in clinical use, and blood tests for all known SARMs have been developed.[103][104] There are a variety of known cases of doping in sports with enobosarm by professional athletes.

List of doping cases edit

Further information: List of doping in sport cases § Enobosarm

In May 2017, Dynamic Technical Formulations voluntarily recalled all lots of Tri-Ton, a dietary supplement that the FDA tested and found to contain Enobosarm and andarine.[105]

In October 2018, UFC fighter Sean O'Malley tested positive for Enobosarm and was suspended by the Nevada State Athletic Commission and USADA for six months. O'Malley tested positive again on May 25, 2019 and was suspended for nine months by the same agencies. USADA determined that none of O'Malley's positive tests were consistent with intentional use and he was allowed to compete at UFC 248 as long as he kept his levels below the threshold of 100 ng/ml.[106]

On January 7, 2019, the College National Football Championship was played between University of Alabama and Clemson University. Prior to the College Football National Championship game, three Clemson players who were suspended — Dexter Lawrence, Braden Galloway and Zach Giellaall — tested positive for a substance known as enobosarm. On June 23, 2019 Clemson did not release enobosarm investigation findings, citing privacy law.[107]

In July 2019, National Football League player Taylor Lewan failed a drug test for Enobosarm, which Lewan claimed he ingested accidentally as an unlabeled ingredient in a supplement.[108]

On October 23, 2020, the Union Cycliste Internationale (UCI) announced that the Italian rider Matteo Spreafico has been notified of two adverse analytical findings (AAFs) for Enobosarm in two samples collected during the Giro d’Italia on 15–16 October 2020.[109]

On July 6, 2021, during the 2020 Summer Olympics, Brazil women's national volleyball team player Tandara was temporarily suspended for testing positive for enobosarm. The test was carried out and identified by the Brazilian Doping Control Authority (ABDC).[110]

On August 12, 2021, after the 2020 Summer Olympics, Chijindu "CJ" Ujah, A member of the silver medal-winning British 4×100 relay team was temporarily suspended for testing positive for both enobosarm and S-23. The sample was collected post event by the International Testing Agency (ITA) and confirmed two days later as positive. The case was referred to the anti-doping division of the Court of Arbitration for Sport.[111] Finally in February 2022, Great Britain were stripped of their silver medal.[112] In October 2022, Ujah was suspended for 22 months by the ITA.[113]

In October 2021, two Thoroughbred horses named Arafat and Komunist tested positive for enobosarm after races at Woodbine Racetrack. In a decision of the Alcohol and Gaming Commission of Ontario issued May 30, 2022, the horses were declared unplaced in the races in question, and their trainer Robert Gerl was fined $100,000 (as well as forfeiting prize money) and suspended from racing for 20 years.[114]

In May 2022, National Football League Wide receiver DeAndre Hopkins was suspended six games without pay by the NFL for violating the league's performance-enhancing drug policy. According to Hopkins, he tested positive for enobosarm.[115]

In April 2023, British boxer Amir Khan was banned for two years after an anti-doping test revealed the presence of enobosarm following his fight against Kell Brook in February 2022.[116]

May 1, 2024. Star boxer Ryan Garcia tested positive for the performance-enhancing substance Ostarine the day before and the day of his upset win over Devin Haney last month, per a Voluntary Anti-Doping Association letter sent to all parties Wednesday and obtained by ESPN. The samples were taken prior to the fight, but the results weren't known until later. Garcia has 10 days to request that his B-sample be tested. Garcia's A-sample also screened positive for 19-Norandrosterone, but its presence is unconfirmed at this time. Garcia floored Haney three times during the majority decision victory, but that result now stands to be overturned unless the B-sample returns negative, which is rare. [117]



Research edit

Enobosarm is currently under development for the treatment of breast cancer.[1][8][44][45] It was also previously under development for a variety of other potential uses, including treatment of cachexia, Duchenne muscular dystrophy, muscle atrophy or sarcopenia, and stress incontinence.[1][10][2] However, development for all other indications has been discontinued.[1]

Enobosarm was assessed for the treatment of muscle wasting in people with lung cancer in two phase 3 clinical trials.[11][2][12][13] The findings of these trials were reported in 2013.[13] Enobosarm significantly improved lean body mass in the trials, but it was not effective in improving muscle strength, as measured by stair climb power.[11][2][12][13] Consequent to these findings, enobosarm did not gain regulatory approval, and development for this use was terminated.[2] Enobosarm had originally been under development for the treatment of sarcopenia (age-related muscle atrophy).[10] However, the FDA requested a cardiovascular safety study be conducted to proceed with phase 3 trials for this indication.[10] The developer of enobosarm refused to conduct this study due to the considerable costs that would be involved.[10] Instead, it opted to trial enobosarm for muscle wasting in cachexia patients, in whom the FDA was more tolerant to cardiovascular side effects and did not require cardiovascular safety evaluation.[10]

Following negative findings for muscle wasting, enobosarm was evaluated for the treatment of stress urinary incontinence in postmenopausal women.[1][2] It was expected that enobosarm might be effective for this use by strengthening the pelvic floor muscles.[1][2] Enobosarm reached phase 2 clinical trials for this indication, but development was discontinued due to lack of effectiveness in a phase 2 study.[1][2]

Subsequently, enobosarm was repurposed again for the treatment of androgen receptor-positive (AR+) estrogen receptor-positive (ER+) breast cancer.[1][8] As of November 2023, it is in phase 3 clinical trials for the treatment of this type of breast cancer.[1][44][45] Increases in lean body mass and muscle strength as a secondary benefit with enobosarm are also being evaluated in these women.[2][43] These trials are notably employing several-fold higher doses of enobosarm than were assessed in the muscle wasting phase 3 trials (9 mg/day versus 3 mg/day, respectively).[2][43]

In January 2024, it was announced that enobosarm was being developed for prevention of muscle wasting and augmentation of fat loss in combination with glucagon-like peptide-1 (GLP-1) receptor agonists like semaglutide for weight loss.[9] A phase 2b clinical trial for this indication with 3 to 6 mg/day enobosarm in sarcopenic obese or overweight elderly individuals is being prepared.[9]

According to GTx, the original developer of enobosarm, a total of 25 clinical studies have been carried out on more than 1,700 people involving doses from 1 to 100 mg as of 2020.[10][22] However, enobosarm has not yet completed clinical development or been approved for any use.[1][2]

See also edit

References edit

  1. ^ a b c d e f g h i j k l m n o p q r s t u v "Enobosarm - GTx". Adis Insight. Springer Nature Switzerland AG. Retrieved 22 December 2023.
  2. ^ a b c d e f g h i j k l m n o p q r s t u v w x y Christiansen AR, Lipshultz LI, Hotaling JM, Pastuszak AW (March 2020). "Selective androgen receptor modulators: the future of androgen therapy?". Translational Andrology and Urology. 9 (Suppl 2): S135–S148. doi:10.21037/tau.2019.11.02. PMC 7108998. PMID 32257854. Unfortunately, results of recent clinical trials of the SARM GTx-024 (Enobosarm) have tempered expectations for its utility as a therapy for muscle wasting. Early on, GTx-024 appeared to have a very bright future as a treatment for sarcopenia/cachexia. Preliminary clinical trials demonstrated that GTx-024 could increase lean body mass and improve physical function without androgenic side effects (27). However, Enobosarm was dealt a blow after the phase III Prevention and treatment Of muscle Wasting in patients with cancER (POWER) I and II trials, where increases in lean body mass were once again observed, but without improved stair climb power (79,80). Failure to attain both primary endpoints led to a lack of approval by the Food and Drug Administration (FDA), which has cast doubt on the previously charted course for SARMs and has tempered enthusiasm regarding the role of SARMs in the treatment of muscle wasting conditions.
  3. ^ a b c d e f Kim J, Wang R, Veverka KA, Dalton JT (November 2013). "Absorption, distribution, metabolism and excretion of the novel SARM GTx-024 [(S)-N-(4-cyano-3-(trifluoromethyl)phenyl)-3-(4-cyanophenoxy)-2-hydroxy-2-methylpropanamide] in rats". Xenobiotica; the Fate of Foreign Compounds in Biological Systems. 43 (11): 993–1009. doi:10.3109/00498254.2013.788233. PMID 24074268. S2CID 6545249.
  4. ^ a b c d e f g h i j k l m n o p q r s t Coss CC, Jones A, Dalton JT (August 2016). "Pharmacokinetic drug interactions of the selective androgen receptor modulator GTx-024(Enobosarm) with itraconazole, rifampin, probenecid, celecoxib and rosuvastatin". Investigational New Drugs. 34 (4): 458–467. doi:10.1007/s10637-016-0353-8. PMID 27105861. S2CID 24200291.
  5. ^ a b c d e f g h Srinath R, Dobs A (February 2014). "Enobosarm (GTx-024, S-22): a potential treatment for cachexia". Future Oncology. 10 (2): 187–194. doi:10.2217/fon.13.273. PMID 24490605. Pharmacokinetics & metabolism: Enobosarm was shown to have linear pharmacokinetics in single-dose studies in healthy male subjects using doses of 1, 3, 10, 30 and 100 mg. In another study enobosarm was given to healthy subjects at doses of 1, 3, 10 and 30 mg over 14 days. Per data from GTx, Inc., the halflife ranged from 14–21 h with similar mean maximum plasma concentration and exposure in subjects of varying ages (Table 1) [20].
  6. ^ a b c d e f Zilbermint MF, Dobs AS (October 2009). "Nonsteroidal selective androgen receptor modulator Ostarine in cancer cachexia". Future Oncology. 5 (8): 1211–1220. doi:10.2217/fon.09.106. PMID 19852734.
  7. ^ a b c d e f g h i j k l m n o p q r s t u v w Jones A, Coss CC, Steiner MS, Dalton JT (2013). "An overview on selective androgen receptor modulators: Focus on enobosarm". Drugs of the Future. 38 (5): 309–316. doi:10.1358/dof.2013.038.05.1970866. ISSN 0377-8282. S2CID 75202407.
  8. ^ a b c Dai C, Ellisen LW (May 2023). "Revisiting Androgen Receptor Signaling in Breast Cancer". The Oncologist. 28 (5): 383–391. doi:10.1093/oncolo/oyad049. PMC 10166165. PMID 36972361.
  9. ^ a b c d e f "Veru Submits IND Application to FDA for the Development of Enobosarm to Prevent Muscle Loss While Augmenting Fat Loss in Combination with GLP-1 Drugs for Weight Loss". BioSpace. 8 January 2024.
  10. ^ a b c d e f g h i j k l m n o p q r s t Fonseca GW, Dworatzek E, Ebner N, Von Haehling S (August 2020). "Selective androgen receptor modulators (SARMs) as pharmacological treatment for muscle wasting in ongoing clinical trials". Expert Opinion on Investigational Drugs. 29 (8): 881–891. doi:10.1080/13543784.2020.1777275. PMID 32476495. S2CID 219174372. [...] to proceed with enobosarm into a phase III clinical trial in patients with sarcopenia, the FDA requested a cardiovascular safety study, which the manufacturer refused to undertake due to considerable costs and decided to test enobosarm in cancer cachexia patients in whom the FDA was more tolerant to the long-term cardiovascular side effects [67]. [...] Enobosarm promotes a similar anabolic response compared with DHT via muscle AR activation, [...] [35]. In a recent study with ovariectomized mice, the weight of the musculus gastrocnemius has been shown to be higher in all groups treated with ostarine as well as bone mineral density and bone biomechanical properties [15]. Moreover, the stimulation of reproductive organs with enobosarm seems to be less pronounced compared to testosterone administration [36] due to its partial agonist and antagonist effect on other androgen-dependent tissues such as prostate and seminal vesicles [37]. [...] In the POWER trials (POWER 1, NCT01355484 and POWER 2, NCT01355497; Table 1), double-blind, placebo-controlled, and multi-center phase III studies [40], patients with non-small-cell lung cancer were given 3 mg of enobosarm or placebo for five months. Despite a lower rate of decline in body weight in the group treated with enobosarm in POWER 1, patients increased LBM at day 84 and day 147 in POWER 1 (+0.41 kg) and POWER 2 (+0.47 kg) compared with patients receiving placebo. However, no physical function improvement has been reported in both studies [41].
  11. ^ a b c d e f g h Wu C, Kovac JR (October 2016). "Novel Uses for the Anabolic Androgenic Steroids Nandrolone and Oxandrolone in the Management of Male Health". Current Urology Reports. 17 (10): 72. doi:10.1007/s11934-016-0629-8. PMID 27535042. S2CID 43199715. Enobosarm has also been evaluated in two phase III clinical trials entitled Prevention and treatment Of muscle Wasting in patiEnts with Cancer 1 and 2 (POWER1 (NCT01355484) and POWER2 (NCT01355497)). [...] The co-primary endpoints of this trial were lean body mass (LBM) response and physical function response for enobosarm vs. placebo after 3 months of treatment. Beneficial effects on both LBM and physical function were found in POWER1, and benefit to LBM but equivocal effects on physical function were found in POWER2.
  12. ^ a b c d e f g h i j k l Mohideen H, Hussain H, Dahiya DS, Wehbe H (February 2023). "Selective Androgen Receptor Modulators: An Emerging Liver Toxin". Journal of Clinical and Translational Hepatology. 11 (1): 188–196. PMC 9647117. PMID 36479151. 17α-alkylated AASs have been modified to be more resistant to liver degradation so that they have decreased first-pass metabolism, allowing for better oral bioavailability and more stable serum levels. However, reduced liver clearance increases the potential for hepatotoxicity.19 Much like this class of AASs, SARMs have been designed for adequate oral bioavailability with decreased liver degradation which would likely create a similar potential for hepatotoxicity.8,15 [...] Ostarine was the first SARM to undergo a phase III clinical trial. The POWER1 and POWER2 trials were two identical randomized, double-blind, placebo-controlled studies to evaluate the efficacy of Ostarine for the treatment of muscle wasting in non-small cell lung cancer. Participants were given 3 mg of Ostarine versus placebo. No study results were published; but GTx Incorporated reported that Ostarine failed to meet endpoints for improvement in lean body mass and physical function compared with placebo.
  13. ^ a b c d "GTX Reports Results for Enobosarm POWER Trials for the Prevention and Treatment of Muscle Wasting in Patients with Non-Small Cell Lung Cancer" (Press release). 19 August 2013.
  14. ^ a b Tauchen J, Jurášek M, Huml L, Rimpelová S (February 2021). "Medicinal Use of Testosterone and Related Steroids Revisited". Molecules. 26 (4): 1032. doi:10.3390/molecules26041032. PMC 7919692. PMID 33672087.
  15. ^ a b Solomon ZJ, Mirabal JR, Mazur DJ, Kohn TP, Lipshultz LI, Pastuszak AW (January 2019). "Selective Androgen Receptor Modulators: Current Knowledge and Clinical Applications". Sexual Medicine Reviews. 7 (1): 84–94. doi:10.1016/j.sxmr.2018.09.006. PMC 6326857. PMID 30503797.
  16. ^ a b c d e f g h i j k l m n Choi SM, Lee BM (2015). "Comparative safety evaluation of selective androgen receptor modulators and anabolic androgenic steroids". Expert Opinion on Drug Safety. 14 (11): 1773–1785. doi:10.1517/14740338.2015.1094052. PMID 26401842. S2CID 8104778. Anabolic androgenic steroids (AASs) comprise synthetic derivatives of testosterone. AASs bind directly to the cytosolic androgen receptor (AR), which is widely distributed across reproductive and non-reproductive tissues, including the prostate, skeletal muscle, liver, skin, and central nervous system (CNS). This binding results in various physiological activities [1], the major one being a masculinizing effect in the skeletal muscle via muscle building [2].
  17. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai Machek SB, Cardaci TD, Wilburn DT, Willoughby DS (December 2020). "Considerations, possible contraindications, and potential mechanisms for deleterious effect in recreational and athletic use of selective androgen receptor modulators (SARMs) in lieu of anabolic androgenic steroids: A narrative review". Steroids. 164: 108753. doi:10.1016/j.steroids.2020.108753. PMID 33148520. S2CID 225049089. Additionally, reported SARM-induced fat free mass increases are a mere fraction of that reported in modest doses of testosterone derivatives in similar timeframes (~1.5kg versus ~7kg in SARMs and testosterone, respectively) [21].
  18. ^ a b c d e f g h i j k l m n o p q r s t u Mohler ML, Nair VA, Hwang DJ, Rakov IM, Patil R, Miller DD (2005-10-28). "Nonsteroidal tissue selective androgen receptor modulators: a promising class of clinical candidates". Expert Opinion on Therapeutic Patents. 15 (11). Informa Healthcare: 1565–1585. doi:10.1517/13543776.15.11.1565. ISSN 1354-3776. S2CID 96279138.
  19. ^ a b Proverbs-Singh T, Feldman JL, Morris MJ, Autio KA, Traina TA (June 2015). "Targeting the androgen receptor in prostate and breast cancer: several new agents in development". Endocrine-Related Cancer. 22 (3): R87–R106. doi:10.1530/ERC-14-0543. PMC 4714354. PMID 25722318. Selective AR modulators (SARMs) are a class of drugs in development; unlike androgen synthesis inhibitors, they act as selective androgen agonists and show promise as a potential therapeutic strategy in BCa. Enobosarm (GTx024) is the farthest along in clinical development, and demonstrates an agonist effect that in some populations inhibits BCa growth. Preclinical data show antitumor activity of GTx-024 in ARC stably expressing cell lines MCF-7 (ERC) and MDA-MB-231 (TNBC) implanted subcutaneously into nude mice. Tumor growth was reduced more than 75% in MDA-MB-231-AR cells and 50% in MCF-7-AR cells compared with vehicle-treated tumors, demonstrating benefit (Dalton et al. 2013).
  20. ^ a b c d e f g h i j k Feingold KR, Anawalt B, Blackman MR, Boyce A, Chrousos G, Corpas E, et al. (5 October 2020). "Androgen Physiology, Pharmacology, Use and Misuse". Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc. PMID 25905231.
  21. ^ Zajac JD, Seeman E, Russell N, Ramchand SK, Bretherton I, Grossmann M, et al. (2020). "Testosterone". Encyclopedia of Bone Biology. Academic Press. pp. 533–550. ISBN 978-0-12-814082-6.
  22. ^ a b "GTx, Inc. Release: Enobosarm Meets Pre-Specified Primary Efficacy Endpoint In Ongoing Phase 2 Clinical Trial In ER+/AR+ Breast Cancer". BioSpace. 28 November 2016. Enobosarm, a selective androgen receptor modulator (SARM) has been evaluated in 24 completed or ongoing clinical trials enrolling over 1,500 subjects, of which approximately 1,000 subjects were treated with enobosarm at doses ranging from 0.1 mg to 100 mg.
  23. ^ a b c Leciejewska N, Jędrejko K, Gómez-Renaud VM, Manríquez-Núñez J, Muszyńska B, Pokrywka A (December 2023). "Selective androgen receptor modulator use and related adverse events including drug-induced liver injury: Analysis of suspected cases". European Journal of Clinical Pharmacology. doi:10.1007/s00228-023-03592-3. PMC 10847181. PMID 38059982.
  24. ^ a b Saner E (24 April 2018). "Why there are more gym supplements in a London fatberg than cocaine and MDMA". The Guardian.
  25. ^ a b c Van Wagoner RM, Eichner A, Bhasin S, Deuster PA, Eichner D (November 2017). "Chemical Composition and Labeling of Substances Marketed as Selective Androgen Receptor Modulators and Sold via the Internet". JAMA. 318 (20): 2004–2010. doi:10.1001/jama.2017.17069. PMC 5820696. PMID 29183075.
  26. ^ a b c d Hahamyan HA, Vasireddi N, Voos JE, Calcei JG (August 2023). "Social media's impact on widespread SARMs abuse". The Physician and Sportsmedicine. 51 (4): 291–293. doi:10.1080/00913847.2022.2078679. PMID 35574698.
  27. ^ a b c d e f Hall E, Vrolijk MF (July 2023). "Androgen Receptor and Cardiovascular Disease: A Potential Risk for the Abuse of Supplements Containing Selective Androgen Receptor Modulators". Nutrients. 15 (15): 3330. doi:10.3390/nu15153330. PMC 10420890. PMID 37571268. Common low-grade side effects of ostarine include headache, nausea, fatigue, and back pain. Other observed effects include increases in alanine transaminase and decreases in HDL, blood glucose, and insulin resistance, all of which returned to normal upon stopping ostarine treatment [1,35]. Information from bodybuilding forums and fitness enthusiasts cited 10 mg to 30 mg daily as the optimal dose for a minimum of 12 weeks, which is 10 times higher than the clinically studied dose, with anecdotal evidence suggesting that taking ostarine for much longer than this can suppress free T levels [1].
  28. ^ a b c d e f g h i j k l m n o Dalton JT, Barnette KG, Bohl CE, Hancock ML, Rodriguez D, Dodson ST, et al. (September 2011). "The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women: results of a double-blind, placebo-controlled phase II trial". Journal of Cachexia, Sarcopenia and Muscle. 2 (3): 153–161. doi:10.1007/s13539-011-0034-6. PMC 3177038. PMID 22031847. The reductions in SHBG [with enobosarm] in men and women (−61% and −80%, respectively, at the 3-mg dose) exceed those observed in men treated with a 600-mg intramuscular testosterone enanthate (−31%) [41].
  29. ^ Bhasin S, Storer TW, Berman N, Callegari C, Clevenger B, Phillips J, et al. (July 1996). "The effects of supraphysiologic doses of testosterone on muscle size and strength in normal men". The New England Journal of Medicine. 335 (1): 1–7. doi:10.1056/NEJM199607043350101. PMID 8637535.
  30. ^ Coss CC, Jones A, Hancock ML, Steiner MS, Dalton JT (2014). "Selective androgen receptor modulators for the treatment of late onset male hypogonadism". Asian Journal of Andrology. 16 (2): 256–261. doi:10.4103/1008-682X.122339. PMC 3955335. PMID 24407183.
  31. ^ a b c d e f g h i j k Coss CC, Jones A, Dalton JT (November 2014). "Selective androgen receptor modulators as improved androgen therapy for advanced breast cancer". Steroids. 90: 94–100. doi:10.1016/j.steroids.2014.06.010. PMID 24945109. S2CID 23450056.
  32. ^ a b c d Vignali JD, Pak KC, Beverley HR, DeLuca JP, Downs JW, Kress AT, et al. (May 2023). "Systematic Review of Safety of Selective Androgen Receptor Modulators in Healthy Adults: Implications for Recreational Users". Journal of Xenobiotics. 13 (2): 218–236. doi:10.3390/jox13020017. PMC 10204391. PMID 37218811.
  33. ^ Bedi H, Hammond C, Sanders D, Yang HM, Yoshida EM (January 2021). "Drug-Induced Liver Injury From Enobosarm (Ostarine), a Selective Androgen Receptor Modulator". ACG Case Reports Journal. 8 (1): e00518. doi:10.14309/crj.0000000000000518. PMC 8337042. PMID 34368386.
  34. ^ Weinblatt D, Roy S (May 2022). "Drug-Induced Liver Injury Secondary to Enobosarm: A Selective Androgen Receptor Modulator". Journal of Medical Cases. 13 (5): 244–248. doi:10.14740/jmc3937. PMC 9119364. PMID 35655632.
  35. ^ Mertens JE, Bömmer MT, Regier MB, Gabriëls G, Pavenstädt H, Grünewald I, et al. (October 2023). "Liver Injury after Selective Androgen Receptor Modulator Intake: A Case Report and Review of the Literature". Zeitschrift Fur Gastroenterologie. doi:10.1055/a-2165-6323. PMID 37871633. S2CID 264426934.
  36. ^ Arayangkool C, Gozun M, Tanariyakul M, Techasatian W, Leesutipornchai T, Nishimura Y (July 2023). "Bile Cast Nephropathy Because of Acute Liver Injury Associated With Selective Androgen Receptor Modulators". ACG Case Reports Journal. 10 (7): e01105. doi:10.14309/crj.0000000000001105. PMC 10371315. PMID 37501938.
  37. ^ a b c d e f g h Kicman AT (June 2008). "Pharmacology of anabolic steroids". British Journal of Pharmacology. 154 (3): 502–521. doi:10.1038/bjp.2008.165. PMC 2439524. PMID 18500378.
  38. ^ Liang JY, Chang HC, Hsu GL (2018). "Penis Endocrinology". In Skinner MK (ed.). Encyclopedia of Reproduction. Elsevier Science. p. 376. ISBN 978-0-12-815145-7. Retrieved 23 December 2023.
  39. ^ Handelsman DJ (July 2022). "History of androgens and androgen action". Best Practice & Research. Clinical Endocrinology & Metabolism. 36 (4): 101629. doi:10.1016/j.beem.2022.101629. PMID 35277356. The next invention was that of the first non-steroidal androgen by Dalton et al. [111] in 1998, six decades after the first non-steroidal estrogen [112]. This creates a new class of non-steroidal synthetic androgen, often termed Specific Androgen Receptor Modulators (SARM), a misleading marketing term rather than an accurate pharmacological description [113,114], usurping a speculative but unsound analogy with Specific Estrogen Receptor Modulators (SERM). [...] none of the non-steroidal androgens under development [116,117] are marketed by 2021. Yet hope springs eternal for this new attempt to separate anabolic from androgenic properties of androgens to facilitate marketing for muscle wasting and other selective effects of testosterone.
  40. ^ Handelsman DJ (May 2011). "Commentary: androgens and "anabolic steroids": the one-headed janus". Endocrinology. 152 (5): 1752–1754. doi:10.1210/en.2010-1501. PMID 21511988. Although development of the first nonsteroidal androgens (17, 18) as candidate selective AR modulators (19) raises hope of resurrecting this defunct term (20), prereceptor activation mechanisms cannot apply to nonsteroidal androgens, and the singular AR lacks a dual drive mechanism of the other paired sex steroid receptors. Consequently, it is not surprising that available knowledge (21) provides only slender hope that this failed, and probably false, dichotomy will now succeed through a renewed search guided by the same in vivo bioassay.
  41. ^ "FDA In Brief: FDA warns against using SARMs in body-building products". Retrieved 1 August 2019.
  42. ^ a b Lim E, Tarulli G, Portman N, Hickey TE, Tilley WD, Palmieri C (December 2016). "Pushing estrogen receptor around in breast cancer". Endocrine-Related Cancer. 23 (12): T227–T241. doi:10.1530/ERC-16-0427. PMID 27729416.
  43. ^ a b c d Kassem L, Shohdy KS, Makady NF, Salem DS, Ebrahim N, Eldaly M (2019-11-16). "Efficacy and Safety of Targeting Androgen Receptor in Advanced Breast Cancer: A Systematic Review". Current Cancer Therapy Reviews. 15 (3): 197–206. doi:10.2174/1573394714666180821145032. S2CID 58234934. It is worth noting that SARMs were initially developed to get benefit of their anabolic effect on muscle and bone without much harm to other tissues. One randomized controlled trial [28], recruited male and females with cancer and weight loss showed that enobosarm 1 mg or 3 mg was associated with significant increase in lean body mass compared to placebo. This led to another ongoing trial, with more selection, aiming to evaluate enobosarm (with higher doses 9 or 18 mg) effect on physical function and lean body mass of ER+/AR+ breast cancer patients (NCT02463032). Such additional action of this class of drugs carries major hope for patients with AR-positive advanced breast cancer, where weight loss, muscle weakness and physical inactivity represent a big challenge for the patient's quality of life (QOL).
  44. ^ a b c Hackbart H, Cui X, Lee JS (October 2023). "Androgen receptor in breast cancer and its clinical implication". Translational Breast Cancer Research. 4: 30. doi:10.21037/tbcr-23-44. PMC 10632549. PMID 37946721.
  45. ^ a b c Ma J, Chan JJ, Toh CH, Yap YS (September 2023). "Emerging systemic therapy options beyond CDK4/6 inhibitors for hormone receptor-positive HER2-negative advanced breast cancer". npj Breast Cancer. 9 (1): 74. doi:10.1038/s41523-023-00578-3. PMC 10491615. PMID 37684290.
  46. ^ a b c d e f Thevis M, Kuuranne T, Geyer H, Schänzer W (January 2017). "Annual banned-substance review: analytical approaches in human sports drug testing". Drug Testing and Analysis. 9 (1): 6–29. doi:10.1002/dta.2139. PMID 27885819. New information on elimination kinetics and potential drug-drug interactions of the SARM GTx-024 (Enobosarm, Ostarine, S-22, MK-2866) was presented by Coss et al. indicating maximum plasma concentrations of the intact drug and its glucuronic acid conjugate of ca. 60 and 100 ng/mL, respectively, reached between 1 and 2 h following an oral dose of 3 mg.[85] The CYP3A4 inhibitor itraconazole did not affect pharmacokinetic parameters of GTx-024, while the CYP3A4 inducer rifampin reduced maximum plasma concentrations significantly. Conversely, the UGT-inhibitor probenecid increased levels of both GTx-024 and its glucuronide.
  47. ^ a b c d e f g Zhang X, Sui Z (February 2013). "Deciphering the selective androgen receptor modulators paradigm". Expert Opinion on Drug Discovery. 8 (2): 191–218. doi:10.1517/17460441.2013.741582. PMID 23231475. S2CID 2584722. The structure and name of Ostarine (GTx-024, MK-2866, Enobosarm, S-22) were disclosed by the USAN Council in November 2011 to establish it as a first member of a new class of drugs furthest in clinical development (Structure 2 in Scheme 1).
  48. ^ a b c d e Kim J, Wu D, Hwang DJ, Miller DD, Dalton JT (October 2005). "The para substituent of S-3-(phenoxy)-2-hydroxy-2-methyl-N-(4-nitro-3-trifluoromethyl-phenyl)-propionamides is a major structural determinant of in vivo disposition and activity of selective androgen receptor modulators". The Journal of Pharmacology and Experimental Therapeutics. 315 (1): 230–239. doi:10.1124/jpet.105.088344. PMID 15987833. S2CID 30799845.
  49. ^ a b c d e f Jones A, Hwang DJ, Duke CB, He Y, Siddam A, Miller DD, et al. (August 2010). "Nonsteroidal selective androgen receptor modulators enhance female sexual motivation". J Pharmacol Exp Ther. 334 (2): 439–48. doi:10.1124/jpet.110.168880. PMC 2913771. PMID 20444881.
  50. ^ Miner JN, Chang W, Chapman MS, Finn PD, Hong MH, López FJ, et al. (January 2007). "An orally active selective androgen receptor modulator is efficacious on bone, muscle, and sex function with reduced impact on prostate". Endocrinology. 148 (1): 363–73. doi:10.1210/en.2006-0793. PMID 17023534.
  51. ^ a b c d e f Narayanan R, Coss CC, Dalton JT (April 2018). "Development of selective androgen receptor modulators (SARMs)". Molecular and Cellular Endocrinology. 465: 134–142. doi:10.1016/j.mce.2017.06.013. PMC 5896569. PMID 28624515.
  52. ^ a b Gao W, Dalton JT (February 2007). "Ockham's razor and selective androgen receptor modulators (SARMs): are we overlooking the role of 5alpha-reductase?". Molecular Interventions. 7 (1): 10–13. doi:10.1124/mi.7.1.3. PMC 2040232. PMID 17339601.
  53. ^ a b Bhasin S, Jasuja R (May 2009). "Selective androgen receptor modulators as function promoting therapies". Current Opinion in Clinical Nutrition and Metabolic Care. 12 (3): 232–240. doi:10.1097/MCO.0b013e32832a3d79. PMC 2907129. PMID 19357508. At the doses that have been tested, the first generation SARMs induce modest gains in lean body mass in healthy volunteers, which are nowhere near the much greater gains in skeletal muscle mass reported with supraphysiological doses of testosterone. The modest gains of 1.0 to 1.5 kg in fat-free mass with first generation SARMs over 4–6 weeks should be contrasted with the 5–7 kg gains in fat-free mass with 300 and 600 mg doses of testosterone enanthate. However, it is possible that next generation of SARM molecules will have greater potency and selectivity than the first generation SARMs.
  54. ^ Hohl A, Marcelli M (2023). "Androgen Receptor in Health and Disease". In Hohl A (ed.). Testosterone. Cham: Springer International Publishing. pp. 21–75. doi:10.1007/978-3-031-31501-5_2. ISBN 978-3-031-31500-8. Physiologically N/C interaction is indispensable because it delays ligand dissociation from the receptor, protects the ligand binding pocket, and prevents receptor degradation [118]. That N/C interaction is essential in AR physiology is demonstrated by the identification of AR LBD mutations resulting in androgen insensitivity syndromes (AIS) that disrupt N/C interaction without affecting the equilibrium binding affinity for the ligand [119, 120].
  55. ^ He B, Wilson EM (April 2002). "The NH(2)-terminal and carboxyl-terminal interaction in the human androgen receptor". Mol Genet Metab. 75 (4): 293–8. doi:10.1016/S1096-7192(02)00009-4. PMID 12051960.
  56. ^ a b Dalton JT, Taylor RP, Mohler ML, Steiner MS (December 2013). "Selective androgen receptor modulators for the prevention and treatment of muscle wasting associated with cancer". Current Opinion in Supportive and Palliative Care. 7 (4): 345–351. doi:10.1097/SPC.0000000000000015. PMID 24189892. S2CID 35120033. Enobosarm was discovered in 2004 as a hyper-myoanabolic SARM that dissociated the anabolic from androgenic effects of AR in terms of potency (ED50) and efficacy (Emax) [29]. Levator ani muscle weight was increased to 131 and 136% of intact controls in intact and castrated (maintenance mode) rats, respectively, without significant increases in ventral prostate and seminal vesicles weights. Importantly, increases in levator ani muscle weight were associated with increases in muscle strength (soleus) in rats. Enobosarm also exerted in-vivo osteoanabolic effects alone and synergistically with alendronate in terms of bone density, strength, and structure [30], which was explained by in-vitro mechanistic studies that demonstrated antiresorptive (osteoclast inhibition) and anabolic (osteoblast differentiation) effects [31].
  57. ^ Dubois V, Simitsidellis I, Laurent MR, Jardi F, Saunders PT, Vanderschueren D, et al. (December 2015). "Enobosarm (GTx-024) Modulates Adult Skeletal Muscle Mass Independently of the Androgen Receptor in the Satellite Cell Lineage". Endocrinology. 156 (12): 4522–4533. doi:10.1210/en.2015-1479. hdl:20.500.11820/072a494a-dfdc-4785-8f77-1a4e7e40e07a. PMID 26393303.
  58. ^ a b Narayanan R, Coss CC, Yepuru M, Kearbey JD, Miller DD, Dalton JT (November 2008). "Steroidal androgens and nonsteroidal, tissue-selective androgen receptor modulator, S-22, regulate androgen receptor function through distinct genomic and nongenomic signaling pathways". Molecular Endocrinology. 22 (11): 2448–2465. doi:10.1210/me.2008-0160. PMID 18801930.
  59. ^ Xie Y, Tian Y, Zhang Y, Zhang Z, Chen R, Li M, et al. (February 2022). "Overview of the development of selective androgen receptor modulators (SARMs) as pharmacological treatment for osteoporosis (1998-2021)". European Journal of Medicinal Chemistry. 230: 114119. doi:10.1016/j.ejmech.2022.114119. PMID 35063736. S2CID 245941791. Similar to other N-arylpropionamide SARMs, in male rats treated for 14 days at 1 mg/day dose S-22 (17) exhibited increased levator ani muscle weight but significantly reduced prostate weight [...]
  60. ^ Le-Rademacher JG, Crawford J, Evans WJ, Jatoi A (September 2017). "Overcoming obstacles in the design of cancer anorexia/weight loss trials". Critical Reviews in Oncology/Hematology. 117: 30–37. doi:10.1016/j.critrevonc.2017.06.008. PMC 5561667. PMID 28807233.
  61. ^ Lambert CP (June 2021). "Should the FDA's criteria for the clinical efficacy of cachexia drugs be changed? Is Ostarine safe and effective?". Journal of Cachexia, Sarcopenia and Muscle. 12 (3): 531–532. doi:10.1002/jcsm.12695. PMC 8200429. PMID 33759397.
  62. ^ Ramage MI, Skipworth RJ (December 2018). "The relationship between muscle mass and function in cancer cachexia: smoke and mirrors?". Current Opinion in Supportive and Palliative Care. 12 (4): 439–444. doi:10.1097/SPC.0000000000000381. hdl:20.500.11820/2b90be5b-7682-4681-a85d-101d3abe3ed9. PMID 30138131.
  63. ^ Brooks A, Schumpp A, Dawson J, Andriello E, Fairman CM (2023). "Considerations for designing trials targeting muscle dysfunction in exercise oncology". Frontiers in Physiology. 14: 1120223. doi:10.3389/fphys.2023.1120223. PMC 9972098. PMID 36866171.
  64. ^ Bhasin S, Woodhouse L, Casaburi R, Singh AB, Bhasin D, Berman N, et al. (December 2001). "Testosterone dose-response relationships in healthy young men". American Journal of Physiology. Endocrinology and Metabolism. 281 (6): E1172–E1181. doi:10.1152/ajpendo.2001.281.6.E1172. PMID 11701431. S2CID 2344757. The administration of the GnRH agonist plus graded doses of testosterone resulted in mean nadir testosterone concentrations of 253, 306, 542, 1,345, and 2,370 ng/dl at the 25-, 50-, 125-, 300-, and 600-mg doses, respectively. Fat-free mass increased dose dependently in men receiving 125, 300, or 600 mg of testosterone weekly (change +3.4, 5.2, and 7.9 kg, respectively). The changes in fat-free mass were highly dependent on testosterone dose (P = 0.0001) and correlated with log testosterone concentrations (r = 0.73, P = 0.0001).
  65. ^ Pan MM, Kovac JR (April 2016). "Beyond testosterone cypionate: evidence behind the use of nandrolone in male health and wellness". Transl Androl Urol. 5 (2): 213–9. doi:10.21037/tau.2016.03.03. PMC 4837307. PMID 27141449.
  66. ^ Bond P, Smit DL, de Ronde W (2022). "Anabolic-androgenic steroids: How do they work and what are the risks?". Frontiers in Endocrinology. 13: 1059473. doi:10.3389/fendo.2022.1059473. PMC 9837614. PMID 36644692. Anabolic–androgenic steroids (AAS) are a class of natural and synthetic hormones that owe their name to their chemical structure (the steroid nucleus, see Figure 1) and the biological effects (anabolic and androgenic) they induce. Anabolic refers to the skeletal muscle-building properties of AAS, whereas androgenic refers to the induction and maintenance of male secondary sexual characteristics (which in principle includes the anabolic action, thereby rendering the term an oxymoron (1)).
  67. ^ Basaria S, Collins L, Dillon EL, Orwoll K, Storer TW, Miciek R, et al. (January 2013). "The safety, pharmacokinetics, and effects of LGD-4033, a novel nonsteroidal oral, selective androgen receptor modulator, in healthy young men". The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences. 68 (1): 87–95. doi:10.1093/gerona/gls078. PMC 4111291. PMID 22459616.
  68. ^ Alén M, Rahkila P (December 1988). "Anabolic-androgenic steroid effects on endocrinology and lipid metabolism in athletes". Sports Medicine. 6 (6): 327–332. doi:10.2165/00007256-198806060-00001. PMID 3068771. S2CID 37898289.
  69. ^ Sinnecker G, Köhler S (June 1989). "Sex hormone-binding globulin response to the anabolic steroid stanozolol: evidence for its suitability as a biological androgen sensitivity test". The Journal of Clinical Endocrinology and Metabolism. 68 (6): 1195–1200. doi:10.1210/jcem-68-6-1195. PMID 2723028.
  70. ^ Eisenfeld AJ, Aten RF (1987). "Estrogen receptors and androgen receptors in the mammalian liver". Journal of Steroid Biochemistry. 27 (4–6): 1109–1118. doi:10.1016/0022-4731(87)90197-x. PMID 3320548. Parenteral routes of sex steroid administration. Liver effects could also be diminished by using routes of administration other than oral. First pass effects would be avoided. [...] Although this discussion has focused predominantly on contraceptives, similar principles seem applicable for diminishing the liver side-effects of androgenic preparations. Thus, androgens should be selected which are likely to be metabolized on entering the hepatocyte and a parenteral route of administration may be preferable. Androgens which are not 17 alkylated might produce fewer liver side-effects than 17 alkylated derivatives judging from their relative effects on plasma protein levels [Z].
  71. ^ Lax ER (1987). "Mechanisms of physiological and pharmacological sex hormone action on the mammalian liver". Journal of Steroid Biochemistry. 27 (4–6): 1119–1128. doi:10.1016/0022-4731(87)90198-1. PMID 3320549. Androgen and oestrogen receptors have been demonstrated in mammalian liver, but since it is generally accepted that they are probably non-functional at endogenous steroid concentrations, it is not apparent how they mediate physiological influences on this organ. Nor is it certain to what extent pharmacological actions of sex hormones reflect overstimulation of physiological routes or whether alternative mechanisms become available once threshold values have been reached. [...] Many of the dangers inherent in synthetic androgen or anabolic steroid therapy may be due less to the androgenic characteristics than to the structural modifications performed to prevent [hepatic] inactivation (e.g. insertion of an acetylene group at 17α).
  72. ^ a b "Enobosarm". PubChem. U.S. National Library of Medicine.
  73. ^ a b "Enobosarm". DrugBank.
  74. ^ a b Cleve A, Fritzemeier KH, Haendler B, Heinrich N, Möller C, Schwede W, et al. (2013). "Pharmacology and Clinical Use of Sex Steroid Hormone Receptor Modulators". Sex and Gender Differences in Pharmacology. Handbook of Experimental Pharmacology. Vol. 214. pp. 543–587. doi:10.1007/978-3-642-30726-3_24. ISBN 978-3-642-30725-6. PMID 23027466. Both male (androgens) and female (oestrogens, progestins) sex hormones are steroid hormones. [...] these compounds have several properties in common: they are small, very lipophilic molecules with the potential to freely diffuse through cell membranes. Their receptors also share important features: in all animals, the receptors for steroid hormones are part of the nuclear receptor superfamily of ligand-triggered transcription factors (Mangelsdorf et al. 1995). Unlike membrane receptors that trigger intracellular signalling pathways, these receptors work by influencing gene expression in the cell.
  75. ^ a b Yoon JH, Kwon KS (June 2021). "Receptor-Mediated Muscle Homeostasis as a Target for Sarcopenia Therapeutics". Endocrinology and Metabolism. 36 (3): 478–490. doi:10.3803/EnM.2021.1081. PMC 8258343. PMID 34218646. Intracellular receptors account for 10% to 15% of drugs on the market, including drugs that act on cytoplasmic receptors such as androgen receptors (ARs), estrogen receptors, progesterone receptors, and glucocorticoid receptors, and other drugs that act on nuclear receptors such as vitamin D receptor (VDR), thyroid hormone receptors, and peroxisome proliferator-activated receptors [27-30]. Ligands of intracellular receptors include lipophilic vitamins, steroid hormones, and small chemicals such as hydrogen peroxide and nitric oxide, which require membrane permeability for intracellular delivery [30,31]. There are several barriers to the intracellular delivery of therapeutic drugs, such as lysosome degradation and active efflux out of the cell. Lowmolecular-weight lipophilic compounds can diffuse directly into cells, whereas high-molecular-weight compounds usually need membrane transporters or endocytosis [32,33]. Proper entry into the cell and subsequent contact with the exact target lead to better therapeutic effects and reduce undesirable adverse effects [34].
  76. ^ Mohd Fauzi F, Koutsoukas A, Cunningham A, Gallegos A, Sedefov R, Bender A (July 2013). "Computer-aided (in silico) approaches in the mode-of-action analysis and safety assessment of ostarine and 4-methylamphetamine". Human Psychopharmacology. 28 (4): 365–378. doi:10.1002/hup.2322. PMID 23881885. S2CID 22800581.
  77. ^ Gao W, Bohl CE, Dalton JT (September 2005). "Chemistry and structural biology of androgen receptor". Chemical Reviews. 105 (9): 3352–3370. doi:10.1021/cr020456u. PMC 2096617. PMID 16159155.
  78. ^ a b Chen J, Kim J, Dalton JT (June 2005). "Discovery and therapeutic promise of selective androgen receptor modulators". Molecular Interventions. 5 (3): 173–188. doi:10.1124/mi.5.3.7. PMC 2072877. PMID 15994457.
  79. ^ a b Hwang DJ, He Y, Ponnusamy S, Mohler ML, Thiyagarajan T, McEwan IJ, et al. (January 2019). "New Generation of Selective Androgen Receptor Degraders: Our Initial Design, Synthesis, and Biological Evaluation of New Compounds with Enzalutamide-Resistant Prostate Cancer Activity". Journal of Medicinal Chemistry. 62 (2): 491–511. doi:10.1021/acs.jmedchem.8b00973. hdl:2164/13357. PMID 30525603. S2CID 54472127.
  80. ^ Corona G, Rastrelli G, Vignozzi L, Maggi M (June 2012). "Emerging medication for the treatment of male hypogonadism". Expert Opinion on Emerging Drugs. 17 (2): 239–259. doi:10.1517/14728214.2012.683411. PMID 22612692. S2CID 22068249.
  81. ^ Holderbaum A (April 2020). Emerging anabolic drugs: investigation of the in vitro and in vivo metabolism of selective androgen receptor modulators (PDF) (Ph.D. thesis). United Kingdom: Queen's University Belfast.
  82. ^ Ricci F, Buzzatti G, Rubagotti A, Boccardo F (November 2014). "Safety of antiandrogen therapy for treating prostate cancer". Expert Opinion on Drug Safety. 13 (11): 1483–1499. doi:10.1517/14740338.2014.966686. PMID 25270521. S2CID 207488100. Bone-sparing effects of antiandrogen monotherapy might be due to selective AR modulators, tissue-specific and androgen-responsive, not affected by antiandrogen therapy, resulting in testosterone still being active in bone during non-steroidal antiandrogen administration [90].
  83. ^ Allan G, Lai MT, Sbriscia T, Linton O, Haynes-Johnson D, Bhattacharjee S, et al. (January 2007). "A selective androgen receptor modulator that reduces prostate tumor size and prevents orchidectomy-induced bone loss in rats". The Journal of Steroid Biochemistry and Molecular Biology. 103 (1): 76–83. doi:10.1016/j.jsbmb.2006.07.006. PMID 17049844. S2CID 25283876.
  84. ^ Wadhwa VK, Weston R, Parr NJ (June 2011). "Bicalutamide monotherapy preserves bone mineral density, muscle strength and has significant health-related quality of life benefits for osteoporotic men with prostate cancer". BJU International. 107 (12): 1923–1929. doi:10.1111/j.1464-410X.2010.09726.x. PMID 20950306. S2CID 205543615.
  85. ^ a b Mohler ML, Bohl CE, Jones A, Coss CC, Narayanan R, He Y, et al. (June 2009). "Nonsteroidal selective androgen receptor modulators (SARMs): dissociating the anabolic and androgenic activities of the androgen receptor for therapeutic benefit". Journal of Medicinal Chemistry. 52 (12): 3597–3617. doi:10.1021/jm900280m. PMID 19432422. Readers are cautioned to note that the name Ostarine is often mistakenly linked to the chemical structure of 8, which is also known as andarine. The chemical structure of Ostarine has not been publicly disclosed. The authors are unable to provide additional information.
  86. ^ Dart DA, Kandil S, Tommasini-Ghelfi S, Serrano de Almeida G, Bevan CL, Jiang W, et al. (September 2018). "Novel Trifluoromethylated Enobosarm Analogues with Potent Antiandrogenic Activity In Vitro and Tissue Selectivity In Vivo". Molecular Cancer Therapeutics. 17 (9): 1846–1858. doi:10.1158/1535-7163.MCT-18-0037. PMID 29895558.
  87. ^ Pertusati F, Ferla S, Bassetto M, Brancale A, Khandil S, Westwell AD, et al. (October 2019). "A new series of bicalutamide, enzalutamide and enobosarm derivatives carrying pentafluorosulfanyl (SF5) and pentafluoroethyl (C2F5) substituents: Improved antiproliferative agents against prostate cancer". European Journal of Medicinal Chemistry. 180: 1–14. doi:10.1016/j.ejmech.2019.07.001. PMID 31288149. S2CID 195872311.
  88. ^ a b Dalton JT, Mukherjee A, Zhu Z, Kirkovsky L, Miller DD (March 1998). "Discovery of nonsteroidal androgens". Biochemical and Biophysical Research Communications. 244 (1): 1–4. doi:10.1006/bbrc.1998.8209. PMID 9514878.
  89. ^ a b c d WO 2005120483, Dalton JT, Mille DD, Veverka KA, "Selective androgen receptor modulators and methods of use thereof", published 22 December 2005, assigned to University of Tennessee Research Foundation 
  90. ^ a b Negro-Vilar A (October 1999). "Selective androgen receptor modulators (SARMs): a novel approach to androgen therapy for the new millennium". The Journal of Clinical Endocrinology and Metabolism. 84 (10): 3459–3462. doi:10.1210/jcem.84.10.6122. PMID 10522980.
  91. ^ He Y, Yin D, Perera M, Kirkovsky L, Stourman N, Li W, et al. (August 2002). "Novel nonsteroidal ligands with high binding affinity and potent functional activity for the androgen receptor". European Journal of Medicinal Chemistry. 37 (8): 619–634. doi:10.1016/s0223-5234(02)01335-1. PMID 12161060.
  92. ^ a b Yin D, Gao W, Kearbey JD, Xu H, Chung K, He Y, et al. (March 2003). "Pharmacodynamics of selective androgen receptor modulators". The Journal of Pharmacology and Experimental Therapeutics. 304 (3): 1334–1340. doi:10.1124/jpet.102.040840. PMID 12604714. S2CID 14724811.
  93. ^ Perera MA (2003). The pharmacology, pharmacokinetics and metabolism of a novel nonsteroidal selective androgen receptor modulator (Thesis). OCLC 56700020. ProQuest 305301414.[page needed]
  94. ^ Nagle M (7 November 2007). "Merck flexes muscle with GTx deal". Outsourcing Pharma.
  95. ^ Swanekamp K (15 March 2010). "Merck And GTx Go Their Separate Ways". Forbes.
  96. ^ "Enobosarm fails endpoints in Ph III study". The Pharma Letter. 20 August 2013.
  97. ^ Sheffield M (April 4, 2014). "Steiner resigns from GTx". Memphis Business Journal.
  98. ^ Garde D (4 April 2014). "GTx's CEO finds the door as the company moves on from a PhIII failure". FierceBiotech.
  99. ^ . Drug Development Technology. 14 January 2016. Archived from the original on 22 June 2018.
  100. ^ "GTx's Enobosarm Fails Phase II Trial in Stress Urinary Incontinence; Stock Plunges 90%+". Genetic Engineering & Biotechnology News. 21 September 2018. Retrieved 1 August 2019.
  101. ^ Pelosci A (10 January 2022). "FDA Grants Fast Track Designation to Enobosarm in AR+, ER+, HER2- Metastatic Breast Cancer". Cancer Network. Retrieved 27 August 2023.
  102. ^ "Recommended INN: List 69 International Nonproprietary Names for Pharmaceutical Substances (INN)" (PDF). WHO Drug Information. 27 (1). 2013. Enobosarm: (2S)-3-(4-cyanophenoxy)-N-[4-cyano-3-(trifluoromethyl)phenyl]-2-hydroxy-2-methylpropanamide
  103. ^ Thevis M, Kohler M, Schlörer N, Kamber M, Kühn A, Linscheid MW, et al. (May 2008). "Mass spectrometry of hydantoin-derived selective androgen receptor modulators". Journal of Mass Spectrometry. 43 (5): 639–650. Bibcode:2008JMSp...43..639T. doi:10.1002/jms.1364. PMID 18095383.
  104. ^ Thevis M, Kohler M, Thomas A, Maurer J, Schlörer N, Kamber M, et al. (May 2008). "Determination of benzimidazole- and bicyclic hydantoin-derived selective androgen receptor antagonists and agonists in human urine using LC-MS/MS". Analytical and Bioanalytical Chemistry. 391 (1): 251–261. doi:10.1007/s00216-008-1882-6. PMID 18270691. S2CID 206899531.
  105. ^ "Dynamic Technical Formulations, LLC. Issues a Voluntary Nationwide Recall of Tri-Ton Due to the Presence of Andarine and Ostarine". U.S. Food & Drug Administration. May 19, 2017.
  106. ^ Raimondi M (January 22, 2020). "NSAC: Sean O'Malley can fight at UFC 248 in March after serving suspension". ESPN. Retrieved June 9, 2020.
  107. ^ Needelman J (14 September 2020). "Clemson lineman suspended by ncaa for positive ostarine test opens up for first time". Retrieved November 13, 2020.
  108. ^ Bieler D (25 July 2019). "Failed PED test has a highly paid offensive lineman sharing polygraph results". Washington Post. Retrieved 25 July 2019. One of the NFL's highest-paid offensive linemen claimed Wednesday that he did not knowingly take a banned substance he says got him a four-game suspension — and he took a polygraph test in an attempt to prove it.
  109. ^ "UCI statement concerning Matteo Spreafico" (Press release). Union Cycliste Internationale. 4 May 2021.
  110. ^ "Tandara é suspensa por "potencial violação" do antidoping e está fora das Olimpíadas" [Tandara is suspended for “potential anti-doping violation” and is out of the Olympics]. globo.com (in Portuguese). 6 August 2021.
  111. ^ "Tokyo Olympics: Team GB 4x100m relay silver medallist CJ Ujah suspended for suspected doping violation". Sky News. 12 August 2021.
  112. ^ "CJ Ujah: Great Britain lose Tokyo Olympics relay medal after doping violation". BBC. 18 February 2022.
  113. ^ "Public Disclosure of Disposition of Anti-Doping Matter Under Rule 14.3.2 – Chijindu Ujah (GBR)" (PDF). Athletics Integrity Unit. 10 October 2022 [29 September 2022].
  114. ^ "In the Matter of the Horse Racing License Act, 2015, S.0.2015,C.38,Sched.9; And in the Matter of Robert Gerl" (PDF). Retrieved 2 June 2022.
  115. ^ "Cardinals WR DeAndre Hopkins still hopes to reduce six-game suspension". NFL.com. 23 June 2022.
  116. ^ "Amir Khan banned for two years after anti-doping test reveals presence of prohibited substance". BBC.co.uk. 4 April 2023.

[1]

Further reading edit

  • Crawford J, Prado CM, Johnston MA, Gralla RJ, Taylor RP, Hancock ML, et al. (June 2016). "Study Design and Rationale for the Phase 3 Clinical Development Program of Enobosarm, a Selective Androgen Receptor Modulator, for the Prevention and Treatment of Muscle Wasting in Cancer Patients (POWER Trials)". Current Oncology Reports. 18 (6): 37. doi:10.1007/s11912-016-0522-0. PMC 4853438. PMID 27138015.

External links edit

  • Enobosarm (GTx-024; MK-2866; Ostarine; S-22; VERU-024) - Veru Healthcare - AdisInsight
  1. ^ "Boxer Garcia tests positive for banned substance". ESPN.com. 2024-05-02. Retrieved 2024-05-02.

January 01, 1970
enobosarm, ostarine, redirects, here, chemical, structure, mistakenly, linked, name, andarine, also, formerly, known, ostarine, developmental, code, names, 2866, selective, androgen, receptor, modulator, sarm, which, under, development, treatment, androgen, re. Ostarine redirects here For the chemical structure mistakenly linked to the name see Andarine Enobosarm also formerly known as ostarine and by the developmental code names GTx 024 MK 2866 and S 22 is a selective androgen receptor modulator SARM which is under development for the treatment of androgen receptor positive breast cancer in women and for improvement of body composition e g prevention of muscle loss in people taking GLP 1 receptor agonists like semaglutide 1 5 7 8 9 It was also under development for a variety of other indications including treatment of cachexia Duchenne muscular dystrophy muscle atrophy or sarcopenia and stress urinary incontinence but development for all other uses has been discontinued 1 10 2 Enobosarm was evaluated for the treatment of muscle wasting related to cancer in late stage clinical trials and the drug improved lean body mass in these trials but it was not effective in improving muscle strength 11 2 12 10 13 As a result enobosarm was not approved and development for this use was terminated 2 Enobosarm is taken by mouth 2 EnobosarmClinical dataOther namesOstarine GTx 024 MK 2866 S 22 VERU 024 1 Routes ofadministrationBy mouth 2 ATC codeNoneLegal statusLegal statusUS Investigational New DrugPharmacokinetic dataBioavailability100 rats 3 MetabolismCYP3A4 UGT1A1 UGT2B7 4 MetabolitesEnobosarm glucuronide 4 Elimination half life14 24 hours 5 6 4 7 ExcretionFeces 70 urine 21 25 rats 3 IdentifiersIUPAC name 2S 3 4 cyanophenoxy N 4 cyano 3 trifluoromethyl phenyl 2 hydroxy 2 methylpropanamide CAS Number841205 47 8PubChem CID11326715DrugBankDB12078 YChemSpider9501667UNIIO3571H3R8NKEGGD10221ChEMBLChEMBL1738889PDB ligandRLJ PDBe RCSB PDB CompTox Dashboard EPA DTXSID30233006Chemical and physical dataFormulaC 19H 14F 3N 3O 3Molar mass389 334 g mol 13D model JSmol Interactive imageMelting point132 to 136 C 270 to 277 F SMILES O C NC1 CC C C N C C F F F C1 C C O COC2 CC C C N C C2InChI InChI 1S C19H14F3N3O3 c1 18 27 11 28 15 6 2 12 9 23 3 7 15 17 26 25 14 5 4 13 10 24 16 8 14 19 20 21 22 h2 8 27H 11H2 1H3 H 25 26 t18 m0 s1Key JNGVJMBLXIUVRD SFHVURJKSA N verify Known possible side effects of enobosarm include headache fatigue anemia nausea diarrhea back pain adverse lipid changes like decreased high density lipoprotein HDL cholesterol levels changes in sex hormone concentrations like decreased testosterone levels elevated liver enzymes and liver toxicity among others 6 14 15 16 12 The potential masculinizing effects of enobosarm for instance in women have largely not been evaluated and are unknown 17 The potential adverse effects and risks of high doses of enobosarm are also unknown 17 Enobosarm is a nonsteroidal SARM acting as an agonist of the androgen receptor AR the biological target of androgens and anabolic steroids like testosterone and dihydrotestosterone DHT 10 However it shows dissociation of effect between tissues in preclinical studies with agonistic and anabolic effects in muscle and bone agonistic effects in breast and partially agonistic or antagonistic effects in the prostate gland and seminal vesicles 7 10 2 18 19 The AR mediated effects of enobosarm in many other androgen sensitive tissues are unknown 18 20 Enobosarm was first identified in 2004 11 and has been under clinical development since at least 2005 1 18 It is the most well studied SARM of all of the agents that have been developed 21 According to GTx its developer a total of 25 clinical studies have been carried out on more than 1 700 people involving doses from 1 to 100 mg as of 2020 10 22 However enobosarm has not yet completed clinical development or been approved for any use 1 2 As of November 2023 it is in phase 3 clinical trials for the treatment of breast cancer and is in phase 2 studies for improvement of body composition in people taking GLP 1 receptor agonists 1 9 Enobosarm was developed by GTx Inc and is now being developed by Veru Inc 1 Aside from its development as a potential pharmaceutical drug enobosarm is on the World Anti Doping Agency list of prohibited substances and is sold for physique and performance enhancing purposes by black market Internet suppliers 10 17 In one survey 2 7 of young male gym users reporting using SARMs 23 In addition a London wastewater analysis found that enobosarm was the most abundant pharmaceutical drug detected and was more prevalent than recreational drugs like MDMA and cocaine 24 Enobosarm is often used in these contexts at doses greatly exceeding those evaluated in clinical trials with unknown effectiveness and safety 17 Many products sold online that are purported to be enobosarm either contain none or contain other unrelated substances 17 25 Social media has played an important role in facilitating the widespread non medical use of SARMs 26 Contents 1 Medical uses 2 Side effects 3 Overdose 4 Interactions 5 Pharmacology 5 1 Pharmacodynamics 5 2 Pharmacokinetics 5 2 1 Absorption 5 2 2 Distribution 5 2 3 Metabolism 5 2 4 Elimination 6 Chemistry 7 History 8 Society and culture 8 1 Names 8 2 Non medical use 8 3 Doping in sport 8 3 1 List of doping cases 9 Research 10 See also 11 References 12 Further reading 13 External linksMedical uses editEnobosarm is not approved for any medical use and is not available as a licensed pharmaceutical drug as of 2023 1 2 10 17 Side effects editGeneral side effects that have been reported with enobosarm in clinical trials include headache fatigue anemia nausea diarrhea and back pain 6 27 14 Enobosarm has shown dose related adverse effects on serum lipids sex hormone and gonadotropin levels and carrier protein levels in clinical trials 16 17 28 It decreases HDL cholesterol levels reducing them dose dependently by 17 at a dose of 1 mg day and by 27 at a dose of 3 mg day 16 17 28 Decreases in total cholesterol levels and in triglyceride levels have also been seen whereas LDL cholesterol levels are unchanged 16 17 28 In healthy elderly men total testosterone levels decreased significantly at doses of 1 and 3 mg day 31 and 57 respectively whereas levels of free testosterone dihydrotestosterone DHT estradiol luteinizing hormone LH and follicle stimulating hormone FSH did not change significantly at doses up to 3 mg day 16 28 In healthy postmenopausal women LH and FSH decreased significantly only at the 3 mg day dose 17 and 30 respectively whereas levels of total testosterone free testosterone DHT and estradiol did not clearly change relative to placebo 16 17 28 SHBG levels were lowered at doses of 1 to 3 mg day decreasing dramatically by 61 in men and by 80 in women at the 3 mg day dose 16 17 28 For comparison testosterone enanthate by intramuscular injection at a highly supraphysiological dose of 600 mg week resulted in only a 31 decrease in SHBG levels 28 29 Despite the large changes in SHBG levels levels of free testosterone did not significantly change in either men or women 16 17 28 Small but significant increases in hemoglobin and hematocrit and small but significant decreases in fasting blood glucose insulin levels and insulin resistance have been observed with enobosarm at 3 mg day 17 30 28 6 In small short term 3 month clinical trials in healthy elderly or postmenopausal women enobosarm at doses ranging from 0 1 to 3 mg day had mixed effects on sebum production and did not increase body hair growth or cause hirsutism 31 28 These effects are measures of androgenic action in skin and hair follicles 31 In the first study at doses of 0 1 to 3 mg day there were no significant changes relative to placebo in sebum tape scores with enobosarm and there were no consistent increases in Ferriman Gallwey score with most women having no change in score or a decreased score and only one having an increase in score 31 28 In the second study which employed 3 mg day enobosarm there was a significant 1 25 fold increase in sebum production from baseline and a significant 1 5 fold increase in sebum production relative to placebo 31 No differences in sebaceous gland volume were apparent upon histological examination in this study 31 At doses ranging from 0 1 to 18 mg day in clinical trials enobosarm has been associated with elevated liver enzymes in subsets of individuals 12 16 Rates of elevated liver enzymes or of elevated alanine aminotransferase ALT levels have ranged from 0 6 to 33 in these trials 12 16 Liver enzyme elevations with enobosarm are often transient and resolve spontaneously 12 However markedly elevated liver enzymes have occasionally occurred with enobosarm in clinical trials and have necessitated discontinuation 12 There have been several published case reports of hepatotoxicity with enobosarm as of 2023 12 32 23 33 34 35 36 Between 2020 and 2022 there has been a rapid increase in reported cases of liver toxicity with SARMs 32 The hepatotoxicity with SARMs may be related to their resistance to hepatic metabolism analogously to the case of 17a alkylated anabolic steroids 12 SARMs are often advertised and sold on the Internet at doses higher than have been described in the literature 17 27 Sometimes doses are recommended as several fold or more greater than the doses used in clinical trials or seemingly arbitrary doses are advised 17 27 For instance enobosarm has been provided at doses of greater than or equal to 20 mg per serving and recommended by bodybuilders and fitness enthusiasts at doses of 10 to 30 mg day relative to the most widely assessed highest dose in clinical trials of 3 mg day an up to 10 fold difference 17 27 SARMs particularly when used at high or excessive doses for prolonged periods of time may result in substantial suppression of endogenous sex hormones like testosterone and estradiol in turn producing widespread unintended deleterious effects on physiological function 17 As examples SARMs may produce potent anabolic effects with deficiency in important androgenic effects may result in estrogen deficiency with consequences like bone loss among others and due to suppression of the hypothalamic pituitary gonadal axis HPG axis may cause infertility 17 Androgens and anabolic steroids like testosterone dihydrotestosterone DHT nandrolone and oxandrolone which are full agonists of the androgen receptor produce virilizing or masculinizing effects like increased sebum production and acne increased body hair growth scalp hair loss voice deepening increased muscle mass android fat redistribution skeletal changes like widening of the shoulders and skull facial changes and genital growth both in males and females 37 38 17 SARMs which are tissue selective mixed or partial agonists of the androgen receptor are largely uncharacterized in terms of their masculinizing effects but are likely to produce many of the same effects 17 37 39 40 SARMs specifically may be expected to retain masculinizing effects like increased muscle mass and bone changes while possibly having reduced virilizing effects in certain other areas like androgenic skin and hair changes 17 16 31 18 20 Anecdotal reports of masculinization with SARMs in women exist in online forums 26 The United States Food and Drug Administration FDA has cautioned that SARMs could have serious adverse effects ranging from risk of heart attack to stroke and liver damage and has warned against their use in bodybuilding products 41 Overdose editEnobosarm has been assessed in clinical trials at doses ranging from 0 1 to 18 mg day 10 However most research has been done at doses of 0 1 to 3 mg day with two phase 3 clinical trials using a dosage of 3 mg day 2 15 32 17 A few small phase 1 and phase 2 trials of enobosarm for breast cancer have employed doses of 9 to 18 mg day 42 12 2 43 Larger phase 3 trials of enobosarm at a dose of 9 mg day for breast cancer e g ARTEST n 210 are now underway 44 45 Doses of up to 100 mg have been assessed in single dose pharmacokinetic studies and doses of up to 30 mg day have been given in short 14 day pharmacokinetic studies 5 Enobosarm sold via black market Internet suppliers and used non medically is often taken at much higher doses than those used widely in clinical trials e g 10 30 mg day with unknown adverse effects and risks 17 27 Interactions editEnobosarm is a substrate of the cytochrome P450 enzyme CYP3A4 and the UDP glucuronosyltransferase UGT enzymes UGT1A1 and UGT2B7 4 It shows very minimal metabolism by cytochrome P50 enzymes with CYP3A4 merely responsible for the greatest degree of metabolism 4 Since enobosarm is metabolized by CYP3A4 UGT1A1 and UGT2B7 inhibitors and inducers of these enzymes can modify the metabolism and pharmacokinetics of enobosarm 4 The strong CYP3A4 inhibitor itraconazole was shown to have minimal to no influence on the pharmacokinetics of enobosarm whereas the strong CYP3A4 inducer rifampin reduced enobosarm peak levels by 23 elimination half life by 23 and area under the curve levels by 43 46 4 The pan UGT inhibitor probenecid was shown to not affect peak levels of enobosarm but to increase the elimination half life of enobosarm by 78 and to increase area under the curve levels of enobosarm by 50 46 4 Enobosarm had no effect on the pharmacokinetics of celecoxib a CYP2C9 substrate or rosuvastatin a BCRP substrate 4 Based on the preceding findings it was concluded that enobosarm poses low risk for clinically relevant drug interactions 4 Pharmacology editPharmacodynamics edit Enobosarm is a selective androgen receptor modulator SARM or a tissue selective mixed agonist or partial agonist of the androgen receptor AR 20 11 18 This receptor is the biological target of endogenous androgens like testosterone and dihydrotestosterone DHT and of synthetic anabolic steroids like nandrolone and oxandrolone 11 18 37 The affinity Ki of enobosarm for the AR is high and was measured as 3 8 nM in one study or approximately 16 8 of that of DHT 47 48 49 Enobosarm shows enantioselectivity for the AR and has similar but somewhat lower potency than DHT in terms of activating the receptor 7 In addition to general activation of the AR enobosarm induces the N C interaction the interaction of the amino terminus and carboxyl terminus of the AR less potently than does DHT but in any case promotes the N C interaction concentration dependently and to the same maximal extent as DHT 49 The AR is widely expressed in tissues throughout the body including in the prostate gland seminal vesicles genitals gonads skin hair follicles muscle bone heart adrenal cortex liver kidneys and brain among others 18 37 The effects of SARMs including enobosarm in many of these tissues have yet to be characterized 18 20 In any case enobosarm has been demonstrated to have varying full agonist or partial agonist or antagonist actions in specific tissues including potent agonistic and anabolic effects in muscle and bone potent agonistic effects in AR expressing human breast cancer cell lines like MCF 7 and MDA MB 231 19 2 and partially agonistic or antagonistic effects in the prostate gland seminal vesicles and uterus 7 10 2 18 49 Enobosarm has additionally been shown to stimulate sexual motivation in female rats similarly to testosterone 47 49 Although enobosarm has not been specifically assessed in this area another structurally unrelated quinolinone SARM LGD 2226 has shown prosexual effects in male rats comparable to those of the synthetic androgen and anabolic steroid fluoxymesterone as well 2 47 50 The molecular mechanisms underlying the tissue selective effects of enobosarm and other SARMs compared to testosterone and other androgens and anabolic steroids remain unknown 51 17 However recruitment of both coactivators and corepressors instead of only coactivators and resultant differing receptor conformations distinct tissue specific modulation of signaling pathways mediating genomic and non genomic effects and differences in within tissue ligand metabolism and modulation of ligand potency i e potentiation versus lack thereof among others all constitute possible mechanisms 51 17 52 In terms of coregulator recruitment the ratios of coactivators to corepressors vary in different tissues throughout the body and it is thought that SARMs may have agonistic effects in tissues with an excess of coactivators relative to corepressors like muscle and bone and may have partially agonistic or antagonistic effects in tissues with an excess of corepressors over coactivators like the prostate 51 Another mechanism may be that SARMs like enobosarm induce the N C interaction less readily than AR full agonists like DHT 17 47 53 49 Induction of the N C interaction has been associated with the effects of endogenous and exogenous AR agonists for instance virilization and prostate growth 47 49 54 55 In animal studies enobosarm has shown potent muscle promoting effects that were similar to those of testosterone and DHT 7 10 56 57 58 48 In one of the first published studies enobosarm maximally restored prostate weight to 51 seminal vesicle weight to 98 and levator ani muscle weight to 136 in castrated male rats relative to gonadally intact control male rats with an ED50 dose for muscle of 0 03 mg day 56 51 48 For comparison testosterone propionate was able to maximally stimulate levator ani muscle to 104 and prostate weight to 121 with ED50 doses of 0 15 mg day and 0 13 mg day respectively 7 Hence enobosarm was able to stimulate the levator ani muscle to a size greater than that in normal male rats or produced with exogenous testosterone in castrated male rats but was only capable of partially rescuing prostate gland weight 51 48 7 Additionally enobosarm fully maintained or restored levator ani weight at doses that did not affect LH or FSH levels in gonadally intact animals 0 1 mg day 7 As such it was more potent in stimulating muscle than testosterone at doses that did not affect gonadotropin levels 5 7 In gonadally intact male rats enobosarm significantly increased levator ani muscle weight to 131 of intact controls but significantly decreased the weights of the prostate gland and seminal vesicles demonstrating an antagonistic or partially agonistic effect in these tissues 7 In another animal study enobosarm and DHT increased levator ani weights to similar or slightly different extents in intact male rats but DHT strongly increased prostate weight while enobosarm reduced prostate weight 7 59 58 Aside from effects in muscle tissue enobosarm has been assessed and found to completely maintain bone quality and composition in castrated male rats and to partially but not fully prevent bone loss in ovariectomized female rats indicating potent anabolic effects in bone as well 7 In a phase 2 human clinical trial in healthy elderly men and postmenopausal women enobosarm dose dependently increased lean body mass muscle mass across doses of 0 1 0 3 1 and 3 mg day with a significant 1 3 kg gain over placebo at 3 mg day and a non significant 0 7 kg gain over placebo at 1 mg day 10 28 Similarly in two phase 3 clinical trials in men and postmenopausal women with muscle wasting due to non small cell lung cancer enobosarm at 3 mg day significantly increased lean body mass by 0 41 kg and 0 47 kg 10 However enobosarm did not successfully increase muscle strength in these phase 3 trials 10 In any case it has been suggested that the study designs and physical function outcomes in such trials may have been flawed 60 61 62 63 2 The increases in lean body mass that have been seen with employed doses of enobosarm in clinical trials are very modest compared to those produced with supraphysiological doses of testosterone over similar timeframes e g 0 5 1 5 kg with enobosarm versus 5 8 kg with 300 600 mg week intramuscular testosterone enanthate in healthy young men 53 17 64 The effects of higher doses of enobosarm 9 18 mg day on lean body mass and muscle strength are also being evaluated in women with breast cancer 2 43 There is some evidence that women may be more sensitive to lean body mass increases with SARMs specifically GSK 2881078 but potentially also others like enobosarm than men 10 17 In addition to its mixed agonist antagonist activity at the AR enobosarm is likely to also differ from steroidal androgens in its effects due to differences in within tissue ligand metabolism 37 31 18 52 The virilizing and androgenic effects of the traditional steroidal androgens like testosterone in skin hair follicles and the prostate gland are attributed to high expression of 5a reductase in these tissues and consequent local conversion and potentiation into more potent androgens 37 31 18 In the case of testosterone this is via conversion into the 10 fold more potent androgen DHT 31 18 Enobosarm is not subject to this local transformation and potentiation and so is theorized to have greatly reduced effects in these tissues relative to testosterone and certain other steroidal androgens 31 18 20 This is likewise theorized to be the case for non 5a reductase potentiated anabolic steroids like nandrolone and oxandrolone which have high myotrophic androgenic potency ratios in animals 37 The lack of 5a reduction may result in reduced androgenic side effects like scalp hair loss facial and body hair growth and prostate growth 20 65 11 On the other hand although SARMs like enobosarm as well as anabolic steroids may have reduced virilizing effects in skin and hair follicles this is not necessarily the case for virilization in general 37 17 In particular the muscle promoting effects of these agents can be considered a masculinizing effect 16 66 The potential masculinizing effects of enobosarm and SARMs in general are largely uncharacterized and unknown 17 Aside from metabolism differences related to 5a reduction enobosarm has also shown much greater impact in the liver specifically on certain aspects of hepatic protein synthesis like reduction of sex hormone binding globulin SHBG production than even highly supraphysiological doses of parenteral testosterone 28 This phenomenon has also been seen with other SARMs such as LGD 4033 17 32 16 67 as well as with synthetic orally active 17a alkylated anabolic steroids like stanozolol 20 68 69 It can be attributed to the first pass through the liver with oral administration and to the high oral bioavailability and strong resistance to hepatic metabolism of these agents 20 70 71 12 Enobosarm has no estrogenic activity either intrinsic to itself or via its metabolites 31 7 18 20 42 As a result the drug is not expected to have feminizing effects or risk of gynecomastia breast development nor to stimulate estrogen sensitive breast cancer 18 7 SARMs like enobosarm are not ideal agents for androgen replacement therapy as they are not expected to reproduce the full spectrum of effects of testosterone and other androgens including not only AR mediated effects but also notably aromatization into estrogen and required physiological estrogenic effects in bone and brain 20 Enobosarm has been found to be a weak antagonist of the progesterone receptor and hence might have some capacity for antiprogestogenic effects 5 7 Aside from its weak interaction with the progesterone receptor enobosarm is highly selective for the AR and does not bind to other nuclear hormone receptors 7 Pharmacokinetics edit Absorption edit Enobosarm is orally bioavailable due to a lack of extensive first pass metabolism 18 In rats the oral bioavailability of enobosarm was found to be 100 3 Enobosarm is rapidly absorbed with oral administration and reaches maximal concentrations median 1 0 hours range 1 0 2 0 hours following administration 46 5 4 The drug reaches a peak concentration of 56 0 ng mL range 53 1 123 0 ng mL following a single 3 mg dose and a steady state peak of 68 1 ng mL following repeated 3 mg doses 46 4 The pharmacokinetics of enobosarm are linear and proportional over a dose range of 1 to 100 mg in single doses in healthy men 5 7 The pharmacokinetics of enobosarm are similar in young versus elderly individuals 7 A concentration time curve of enobosarm levels following a single oral dose of enobosarm in humans has been published 7 Distribution edit Enobosarm is a small molecule and highly lipophilic compound 72 73 Compounds of this type are typically able to diffuse freely through biological membranes such as cell membranes and barriers like the blood brain barrier 74 75 This is in fact essential for the action of nuclear receptor ligands like enobosarm since their biological targets the androgen receptor in this case are located intracellularly 74 75 One in silico study predicted that on the basis of its overall physicochemical properties but not considering active transport enobosarm would be unlikely to cross the blood brain barrier and hence would be a peripherally selective drug with reduced or no central nervous system effects 76 However in a rat tissue distribution study enobosarm was found to be concentrated in brain tissues to a similar extent as other target tissues like skeletal muscle bone prostate and seminal vesicles 3 This is consistent with enobosarm producing centrally mediated effects in humans like suppression of LH and FSH secretion 16 17 28 Enobosarm does not bind to sex hormone binding globulin 18 Metabolism edit In vitro studies found very minimal metabolism of enobosarm by human cytochrome P450 enzymes 4 The greatest degree of oxidative metabolite generation occurred with CYP3A4 4 Upon incubation with human UDP glucuronosyltransferase UGT enzymes enobosarm glucuronide was generated with a majority of this inactive metabolite being produced by UGT1A1 and UGT2B7 4 Enobosarm glucuronide is the primary circulating metabolite of enobosarm 4 Coadministration of the strong CYP3A4 inhibitor itraconazole had minimal impact on the pharmacokinetics of enobosarm and enobosarm glucuronide whereas the strong CYP3A4 inducer rifampin reduced enobosarm peak levels by 23 elimination half life by 23 and area under the curve levels by 43 46 4 Coadministration of the pan UGT inhibitor probenecid with enobosarm resulted in similar peak levels of enobosarm but the elimination half life of enobosarm was extended by 78 and area under the curve levels increased by 50 46 4 These data are consistent with the preclinical findings that enobosarm is a substrate of CYP3A4 and UGT enzymes 4 The metabolism of enobosarm is similar to that of the closely structurally related drug bicalutamide 3 Elimination edit In rats enobosarm was excreted approximately 70 in feces and 21 to 25 in urine 3 Enobosarm has an elimination half life of approximately 14 to 24 hours in human volunteers 5 6 7 In one pharmacokinetic study the mean terminal half life was 22 0 5 8 SD hours with a range of 13 7 to 31 3 hours in different individuals 4 Chemistry editEnobosarm is a small molecule molecular weight 389 3 g mol and highly lipophilic predicted log P 2 7 3 3 compound 72 73 Enobosarm and related SARMs like acetothiolutamide and andarine acetamidoxolutamide GTx 007 S 4 were derived from structural modification of the arylpropionamide nonsteroidal antiandrogen bicalutamide 77 18 78 20 79 They are nonsteroidal arylpropionamides themselves and are close structural analogues of bicalutamide 18 78 79 80 Bicalutamide was used to derive acetothiolutamide andarine was developed from acetothiolutamide the SARM S 1 was developed from andarine and finally enobosarm was developed from S 1 81 Bicalutamide is used clinically as an antiandrogen but there is some evidence that bicalutamide itself may have some SARM like properties in certain tissues for instance in muscle and bone 82 83 84 Enobosarm S 22 and andarine S 4 and their chemical structures have sometimes been confused 85 The chemical structure of enobosarm was not disclosed until November 2011 47 85 Novel nonsteroidal antiandrogens have been developed from enobosarm with enhanced potency and activity relative to conventional antiandrogens like bicalutamide and enzalutamide 86 87 History editThe first SARMs were arylpropionamides derived from the nonsteroidal antiandrogen bicalutamide 7 88 They were discovered by James T Dalton and colleagues at the University of Tennessee and other institutions and were first described in a paper published in 1998 7 88 89 At the time these AR agonists were referred to as nonsteroidal androgens a drug class that had not been previously described 90 By 1999 however on the basis of the selective estrogen receptor modulator SERM like mixed agonist antagonist and tissue selective activity of these nonsteroidal AR agonists the term selective androgen receptor modulator or SARM was introduced and adoption of this name had begun 90 The arylpropionamide SARM andarine GTx 007 S 4 was first described in the literature by 2002 91 92 93 In 2003 arylpropionamide AR agonists including andarine were first reported to possess SARM type tissue selectivity in vivo 47 92 Enobosarm GTx 024 S 22 another arylpropionamide SARM was first identified in 2004 11 89 and was first described in the literature in 2005 18 48 89 GTx a pharmaceutical company founded in Memphis Tennessee in 1997 licensed the rights to enobosarm from the University of Tennessee Research Foundation and began developing it as a pharmaceutical drug 1 89 A phase 1 clinical trial employing enobosarm had been completed by 2005 18 By 2007 enobosarm was in a phase 2 trial and that year GTx signed an exclusive license agreement for its SARM program with Merck amp Co 94 The companies ended the deal in 2010 95 In August 2011 there was a 12 week double blind placebo controlled phase 2 trial that focused on elderly men and postmenopausal women which concluded that enobosarm showed statistically significant improvements in total lean body mass and physical function without apparent adverse effects on hair growth or sebum production 28 In August 2013 GTx announced that enobosarm had failed in two phase 3 clinical trials to treat wasting in people with lung cancer 96 The company had invested around 35 million in the development of the drug 97 The company said at that time that it planned to pursue approval of enobosarm in Europe the company was also still developing GTx 758 a nonsteroidal estrogen for castration resistant prostate cancer 98 As of 2018 enobosarm was the only SARM to have reached or completed phase 3 clinical trials 51 In 2016 GTx began phase 2 trials to see if enobosarm might be effective to treat stress urinary incontinence in women 99 In 2018 GTx announced the phase 2 trials on the effectiveness of enobosarm for stress urinary incontinence in women failed to achieve its primary endpoint in the ASTRID Trial 100 By September 2023 development of enobosarm for stress urinary incontinence had been discontinued 1 In 2022 the FDA granted fast tract designation to enobosarm in AR ER HER2 metastatic breast cancer 101 In January 2024 Veru Inc submitted an Investigational New Drug application to the FDA of enobosarm for prevention of muscle loss and augmentation of fat loss in combination with glucagon like peptide 1 GLP 1 receptor agonists like semaglutide for weight loss 9 In addition they announced plans to conduct a phase 2b study of enobosarm at doses of 3 to 6 mg day for this purpose in sarcopenic obese or overweight elderly individuals receiving GLP 1 receptor agonists 9 Enobosarm was developed by GTx Inc and is now being developed by Veru Inc 1 Society and culture editNames edit Enobosarm is the generic name of the drug and its International Nonproprietary Name INN 102 Ostarine was a tentative brand name of the drug created by GTx Inc that did not end up being used for marketing purposes but continues to be used as a synonym for the drug 1 6 Enobosarm is also known by the pharmaceutical developmental code names S 22 synthesis paper GTx 024 GTx Inc MK 2866 Merck and VERU 024 Veru Inc 1 Non medical use edit Enobosarm and other SARMs are sold by black market vendors on the Internet 17 25 These agents have increasingly become used by the general public as gym supplements such as pre workout or lifestyle drugs rather than as an aid to performance in athletic or bodybuilding competitions In one survey 2 7 of young male gym users in the Netherlands reporting using SARMs 23 In addition a 2018 analysis of a fatberg from a sewer in central London showed enobosarm to be the most abundant pharmaceutical drug detected and was present at higher concentration than recreational drugs such as MDMA and cocaine While this isolated result may not be representative of overall levels of use for enobosarm to be detectable in sewer deposits reflects significant levels of enobosarm use in the area close to where the sample was collected 24 Doses of enobosarm sold online and used non medically are often many times higher than those assessed in clinical trials 17 27 Aside from enobosarm the other most commonly used SARMs include vosilasarm RAD140 testolone LGD 4033 VK5211 ligandrol and andarine GTx 007 S 4 26 Many products sold online that are purported to be enobosarm either contain none or contain other unrelated substances and doses are also frequently not as labeled 17 25 Social media has played an important role in facilitating the widespread non medical use of SARMs 26 Doping in sport edit SARMs including enobosarm may be and have been used by athletes to assist in training and increase physical stamina and fitness potentially producing effects similar to anabolic steroids For this reason SARMs were banned by the World Anti Doping Agency in January 2008 despite no drugs from this class yet being in clinical use and blood tests for all known SARMs have been developed 103 104 There are a variety of known cases of doping in sports with enobosarm by professional athletes List of doping cases edit Further information List of doping in sport cases Enobosarm In May 2017 Dynamic Technical Formulations voluntarily recalled all lots of Tri Ton a dietary supplement that the FDA tested and found to contain Enobosarm and andarine 105 In October 2018 UFC fighter Sean O Malley tested positive for Enobosarm and was suspended by the Nevada State Athletic Commission and USADA for six months O Malley tested positive again on May 25 2019 and was suspended for nine months by the same agencies USADA determined that none of O Malley s positive tests were consistent with intentional use and he was allowed to compete at UFC 248 as long as he kept his levels below the threshold of 100 ng ml 106 On January 7 2019 the College National Football Championship was played between University of Alabama and Clemson University Prior to the College Football National Championship game three Clemson players who were suspended Dexter Lawrence Braden Galloway and Zach Giellaall tested positive for a substance known as enobosarm On June 23 2019 Clemson did not release enobosarm investigation findings citing privacy law 107 In July 2019 National Football League player Taylor Lewan failed a drug test for Enobosarm which Lewan claimed he ingested accidentally as an unlabeled ingredient in a supplement 108 On October 23 2020 the Union Cycliste Internationale UCI announced that the Italian rider Matteo Spreafico has been notified of two adverse analytical findings AAFs for Enobosarm in two samples collected during the Giro d Italia on 15 16 October 2020 109 On July 6 2021 during the 2020 Summer Olympics Brazil women s national volleyball team player Tandara was temporarily suspended for testing positive for enobosarm The test was carried out and identified by the Brazilian Doping Control Authority ABDC 110 On August 12 2021 after the 2020 Summer Olympics Chijindu CJ Ujah A member of the silver medal winning British 4 100 relay team was temporarily suspended for testing positive for both enobosarm and S 23 The sample was collected post event by the International Testing Agency ITA and confirmed two days later as positive The case was referred to the anti doping division of the Court of Arbitration for Sport 111 Finally in February 2022 Great Britain were stripped of their silver medal 112 In October 2022 Ujah was suspended for 22 months by the ITA 113 In October 2021 two Thoroughbred horses named Arafat and Komunist tested positive for enobosarm after races at Woodbine Racetrack In a decision of the Alcohol and Gaming Commission of Ontario issued May 30 2022 the horses were declared unplaced in the races in question and their trainer Robert Gerl was fined 100 000 as well as forfeiting prize money and suspended from racing for 20 years 114 In May 2022 National Football League Wide receiver DeAndre Hopkins was suspended six games without pay by the NFL for violating the league s performance enhancing drug policy According to Hopkins he tested positive for enobosarm 115 In April 2023 British boxer Amir Khan was banned for two years after an anti doping test revealed the presence of enobosarm following his fight against Kell Brook in February 2022 116 May 1 2024 Star boxer Ryan Garcia tested positive for the performance enhancing substance Ostarine the day before and the day of his upset win over Devin Haney last month per a Voluntary Anti Doping Association letter sent to all parties Wednesday and obtained by ESPN The samples were taken prior to the fight but the results weren t known until later Garcia has 10 days to request that his B sample be tested Garcia s A sample also screened positive for 19 Norandrosterone but its presence is unconfirmed at this time Garcia floored Haney three times during the majority decision victory but that result now stands to be overturned unless the B sample returns negative which is rare 117 Research editEnobosarm is currently under development for the treatment of breast cancer 1 8 44 45 It was also previously under development for a variety of other potential uses including treatment of cachexia Duchenne muscular dystrophy muscle atrophy or sarcopenia and stress incontinence 1 10 2 However development for all other indications has been discontinued 1 Enobosarm was assessed for the treatment of muscle wasting in people with lung cancer in two phase 3 clinical trials 11 2 12 13 The findings of these trials were reported in 2013 13 Enobosarm significantly improved lean body mass in the trials but it was not effective in improving muscle strength as measured by stair climb power 11 2 12 13 Consequent to these findings enobosarm did not gain regulatory approval and development for this use was terminated 2 Enobosarm had originally been under development for the treatment of sarcopenia age related muscle atrophy 10 However the FDA requested a cardiovascular safety study be conducted to proceed with phase 3 trials for this indication 10 The developer of enobosarm refused to conduct this study due to the considerable costs that would be involved 10 Instead it opted to trial enobosarm for muscle wasting in cachexia patients in whom the FDA was more tolerant to cardiovascular side effects and did not require cardiovascular safety evaluation 10 Following negative findings for muscle wasting enobosarm was evaluated for the treatment of stress urinary incontinence in postmenopausal women 1 2 It was expected that enobosarm might be effective for this use by strengthening the pelvic floor muscles 1 2 Enobosarm reached phase 2 clinical trials for this indication but development was discontinued due to lack of effectiveness in a phase 2 study 1 2 Subsequently enobosarm was repurposed again for the treatment of androgen receptor positive AR estrogen receptor positive ER breast cancer 1 8 As of November 2023 it is in phase 3 clinical trials for the treatment of this type of breast cancer 1 44 45 Increases in lean body mass and muscle strength as a secondary benefit with enobosarm are also being evaluated in these women 2 43 These trials are notably employing several fold higher doses of enobosarm than were assessed in the muscle wasting phase 3 trials 9 mg day versus 3 mg day respectively 2 43 In January 2024 it was announced that enobosarm was being developed for prevention of muscle wasting and augmentation of fat loss in combination with glucagon like peptide 1 GLP 1 receptor agonists like semaglutide for weight loss 9 A phase 2b clinical trial for this indication with 3 to 6 mg day enobosarm in sarcopenic obese or overweight elderly individuals is being prepared 9 According to GTx the original developer of enobosarm a total of 25 clinical studies have been carried out on more than 1 700 people involving doses from 1 to 100 mg as of 2020 10 22 However enobosarm has not yet completed clinical development or been approved for any use 1 2 See also editList of investigational sex hormonal agents AndrogenicsReferences edit a b c d e f g h i j k l m n o p q r s t u v Enobosarm GTx Adis Insight Springer Nature Switzerland AG Retrieved 22 December 2023 a b c d e f g h i j k l m n o p q r s t u v w x y Christiansen AR Lipshultz LI Hotaling JM Pastuszak AW March 2020 Selective androgen receptor modulators the future of androgen therapy Translational Andrology and Urology 9 Suppl 2 S135 S148 doi 10 21037 tau 2019 11 02 PMC 7108998 PMID 32257854 Unfortunately results of recent clinical trials of the SARM GTx 024 Enobosarm have tempered expectations for its utility as a therapy for muscle wasting Early on GTx 024 appeared to have a very bright future as a treatment for sarcopenia cachexia Preliminary clinical trials demonstrated that GTx 024 could increase lean body mass and improve physical function without androgenic side effects 27 However Enobosarm was dealt a blow after the phase III Prevention and treatment Of muscle Wasting in patients with cancER POWER I and II trials where increases in lean body mass were once again observed but without improved stair climb power 79 80 Failure to attain both primary endpoints led to a lack of approval by the Food and Drug Administration FDA which has cast doubt on the previously charted course for SARMs and has tempered enthusiasm regarding the role of SARMs in the treatment of muscle wasting conditions a b c d e f Kim J Wang R Veverka KA Dalton JT November 2013 Absorption distribution metabolism and excretion of the novel SARM GTx 024 S N 4 cyano 3 trifluoromethyl phenyl 3 4 cyanophenoxy 2 hydroxy 2 methylpropanamide in rats Xenobiotica the Fate of Foreign Compounds in Biological Systems 43 11 993 1009 doi 10 3109 00498254 2013 788233 PMID 24074268 S2CID 6545249 a b c d e f g h i j k l m n o p q r s t Coss CC Jones A Dalton JT August 2016 Pharmacokinetic drug interactions of the selective androgen receptor modulator GTx 024 Enobosarm with itraconazole rifampin probenecid celecoxib and rosuvastatin Investigational New Drugs 34 4 458 467 doi 10 1007 s10637 016 0353 8 PMID 27105861 S2CID 24200291 a b c d e f g h Srinath R Dobs A February 2014 Enobosarm GTx 024 S 22 a potential treatment for cachexia Future Oncology 10 2 187 194 doi 10 2217 fon 13 273 PMID 24490605 Pharmacokinetics amp metabolism Enobosarm was shown to have linear pharmacokinetics in single dose studies in healthy male subjects using doses of 1 3 10 30 and 100 mg In another study enobosarm was given to healthy subjects at doses of 1 3 10 and 30 mg over 14 days Per data from GTx Inc the halflife ranged from 14 21 h with similar mean maximum plasma concentration and exposure in subjects of varying ages Table 1 20 a b c d e f Zilbermint MF Dobs AS October 2009 Nonsteroidal selective androgen receptor modulator Ostarine in cancer cachexia Future Oncology 5 8 1211 1220 doi 10 2217 fon 09 106 PMID 19852734 a b c d e f g h i j k l m n o p q r s t u v w Jones A Coss CC Steiner MS Dalton JT 2013 An overview on selective androgen receptor modulators Focus on enobosarm Drugs of the Future 38 5 309 316 doi 10 1358 dof 2013 038 05 1970866 ISSN 0377 8282 S2CID 75202407 a b c Dai C Ellisen LW May 2023 Revisiting Androgen Receptor Signaling in Breast Cancer The Oncologist 28 5 383 391 doi 10 1093 oncolo oyad049 PMC 10166165 PMID 36972361 a b c d e f Veru Submits IND Application to FDA for the Development of Enobosarm to Prevent Muscle Loss While Augmenting Fat Loss in Combination with GLP 1 Drugs for Weight Loss BioSpace 8 January 2024 a b c d e f g h i j k l m n o p q r s t Fonseca GW Dworatzek E Ebner N Von Haehling S August 2020 Selective androgen receptor modulators SARMs as pharmacological treatment for muscle wasting in ongoing clinical trials Expert Opinion on Investigational Drugs 29 8 881 891 doi 10 1080 13543784 2020 1777275 PMID 32476495 S2CID 219174372 to proceed with enobosarm into a phase III clinical trial in patients with sarcopenia the FDA requested a cardiovascular safety study which the manufacturer refused to undertake due to considerable costs and decided to test enobosarm in cancer cachexia patients in whom the FDA was more tolerant to the long term cardiovascular side effects 67 Enobosarm promotes a similar anabolic response compared with DHT via muscle AR activation 35 In a recent study with ovariectomized mice the weight of the musculus gastrocnemius has been shown to be higher in all groups treated with ostarine as well as bone mineral density and bone biomechanical properties 15 Moreover the stimulation of reproductive organs with enobosarm seems to be less pronounced compared to testosterone administration 36 due to its partial agonist and antagonist effect on other androgen dependent tissues such as prostate and seminal vesicles 37 In the POWER trials POWER 1 NCT01355484 and POWER 2 NCT01355497 Table 1 double blind placebo controlled and multi center phase III studies 40 patients with non small cell lung cancer were given 3 mg of enobosarm or placebo for five months Despite a lower rate of decline in body weight in the group treated with enobosarm in POWER 1 patients increased LBM at day 84 and day 147 in POWER 1 0 41 kg and POWER 2 0 47 kg compared with patients receiving placebo However no physical function improvement has been reported in both studies 41 a b c d e f g h Wu C Kovac JR October 2016 Novel Uses for the Anabolic Androgenic Steroids Nandrolone and Oxandrolone in the Management of Male Health Current Urology Reports 17 10 72 doi 10 1007 s11934 016 0629 8 PMID 27535042 S2CID 43199715 Enobosarm has also been evaluated in two phase III clinical trials entitled Prevention and treatment Of muscle Wasting in patiEnts with Cancer 1 and 2 POWER1 NCT01355484 and POWER2 NCT01355497 The co primary endpoints of this trial were lean body mass LBM response and physical function response for enobosarm vs placebo after 3 months of treatment Beneficial effects on both LBM and physical function were found in POWER1 and benefit to LBM but equivocal effects on physical function were found in POWER2 a b c d e f g h i j k l Mohideen H Hussain H Dahiya DS Wehbe H February 2023 Selective Androgen Receptor Modulators An Emerging Liver Toxin Journal of Clinical and Translational Hepatology 11 1 188 196 PMC 9647117 PMID 36479151 17a alkylated AASs have been modified to be more resistant to liver degradation so that they have decreased first pass metabolism allowing for better oral bioavailability and more stable serum levels However reduced liver clearance increases the potential for hepatotoxicity 19 Much like this class of AASs SARMs have been designed for adequate oral bioavailability with decreased liver degradation which would likely create a similar potential for hepatotoxicity 8 15 Ostarine was the first SARM to undergo a phase III clinical trial The POWER1 and POWER2 trials were two identical randomized double blind placebo controlled studies to evaluate the efficacy of Ostarine for the treatment of muscle wasting in non small cell lung cancer Participants were given 3 mg of Ostarine versus placebo No study results were published but GTx Incorporated reported that Ostarine failed to meet endpoints for improvement in lean body mass and physical function compared with placebo a b c d GTX Reports Results for Enobosarm POWER Trials for the Prevention and Treatment of Muscle Wasting in Patients with Non Small Cell Lung Cancer Press release 19 August 2013 a b Tauchen J Jurasek M Huml L Rimpelova S February 2021 Medicinal Use of Testosterone and Related Steroids Revisited Molecules 26 4 1032 doi 10 3390 molecules26041032 PMC 7919692 PMID 33672087 a b Solomon ZJ Mirabal JR Mazur DJ Kohn TP Lipshultz LI Pastuszak AW January 2019 Selective Androgen Receptor Modulators Current Knowledge and Clinical Applications Sexual Medicine Reviews 7 1 84 94 doi 10 1016 j sxmr 2018 09 006 PMC 6326857 PMID 30503797 a b c d e f g h i j k l m n Choi SM Lee BM 2015 Comparative safety evaluation of selective androgen receptor modulators and anabolic androgenic steroids Expert Opinion on Drug Safety 14 11 1773 1785 doi 10 1517 14740338 2015 1094052 PMID 26401842 S2CID 8104778 Anabolic androgenic steroids AASs comprise synthetic derivatives of testosterone AASs bind directly to the cytosolic androgen receptor AR which is widely distributed across reproductive and non reproductive tissues including the prostate skeletal muscle liver skin and central nervous system CNS This binding results in various physiological activities 1 the major one being a masculinizing effect in the skeletal muscle via muscle building 2 a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai Machek SB Cardaci TD Wilburn DT Willoughby DS December 2020 Considerations possible contraindications and potential mechanisms for deleterious effect in recreational and athletic use of selective androgen receptor modulators SARMs in lieu of anabolic androgenic steroids A narrative review Steroids 164 108753 doi 10 1016 j steroids 2020 108753 PMID 33148520 S2CID 225049089 Additionally reported SARM induced fat free mass increases are a mere fraction of that reported in modest doses of testosterone derivatives in similar timeframes 1 5kg versus 7kg in SARMs and testosterone respectively 21 a b c d e f g h i j k l m n o p q r s t u Mohler ML Nair VA Hwang DJ Rakov IM Patil R Miller DD 2005 10 28 Nonsteroidal tissue selective androgen receptor modulators a promising class of clinical candidates Expert Opinion on Therapeutic Patents 15 11 Informa Healthcare 1565 1585 doi 10 1517 13543776 15 11 1565 ISSN 1354 3776 S2CID 96279138 a b Proverbs Singh T Feldman JL Morris MJ Autio KA Traina TA June 2015 Targeting the androgen receptor in prostate and breast cancer several new agents in development Endocrine Related Cancer 22 3 R87 R106 doi 10 1530 ERC 14 0543 PMC 4714354 PMID 25722318 Selective AR modulators SARMs are a class of drugs in development unlike androgen synthesis inhibitors they act as selective androgen agonists and show promise as a potential therapeutic strategy in BCa Enobosarm GTx024 is the farthest along in clinical development and demonstrates an agonist effect that in some populations inhibits BCa growth Preclinical data show antitumor activity of GTx 024 in ARC stably expressing cell lines MCF 7 ERC and MDA MB 231 TNBC implanted subcutaneously into nude mice Tumor growth was reduced more than 75 in MDA MB 231 AR cells and 50 in MCF 7 AR cells compared with vehicle treated tumors demonstrating benefit Dalton et al 2013 a b c d e f g h i j k Feingold KR Anawalt B Blackman MR Boyce A Chrousos G Corpas E et al 5 October 2020 Androgen Physiology Pharmacology Use and Misuse Endotext Internet South Dartmouth MA MDText com Inc PMID 25905231 Zajac JD Seeman E Russell N Ramchand SK Bretherton I Grossmann M et al 2020 Testosterone Encyclopedia of Bone Biology Academic Press pp 533 550 ISBN 978 0 12 814082 6 a b GTx Inc Release Enobosarm Meets Pre Specified Primary Efficacy Endpoint In Ongoing Phase 2 Clinical Trial In ER AR Breast Cancer BioSpace 28 November 2016 Enobosarm a selective androgen receptor modulator SARM has been evaluated in 24 completed or ongoing clinical trials enrolling over 1 500 subjects of which approximately 1 000 subjects were treated with enobosarm at doses ranging from 0 1 mg to 100 mg a b c Leciejewska N Jedrejko K Gomez Renaud VM Manriquez Nunez J Muszynska B Pokrywka A December 2023 Selective androgen receptor modulator use and related adverse events including drug induced liver injury Analysis of suspected cases European Journal of Clinical Pharmacology doi 10 1007 s00228 023 03592 3 PMC 10847181 PMID 38059982 a b Saner E 24 April 2018 Why there are more gym supplements in a London fatberg than cocaine and MDMA The Guardian a b c Van Wagoner RM Eichner A Bhasin S Deuster PA Eichner D November 2017 Chemical Composition and Labeling of Substances Marketed as Selective Androgen Receptor Modulators and Sold via the Internet JAMA 318 20 2004 2010 doi 10 1001 jama 2017 17069 PMC 5820696 PMID 29183075 a b c d Hahamyan HA Vasireddi N Voos JE Calcei JG August 2023 Social media s impact on widespread SARMs abuse The Physician and Sportsmedicine 51 4 291 293 doi 10 1080 00913847 2022 2078679 PMID 35574698 a b c d e f Hall E Vrolijk MF July 2023 Androgen Receptor and Cardiovascular Disease A Potential Risk for the Abuse of Supplements Containing Selective Androgen Receptor Modulators Nutrients 15 15 3330 doi 10 3390 nu15153330 PMC 10420890 PMID 37571268 Common low grade side effects of ostarine include headache nausea fatigue and back pain Other observed effects include increases in alanine transaminase and decreases in HDL blood glucose and insulin resistance all of which returned to normal upon stopping ostarine treatment 1 35 Information from bodybuilding forums and fitness enthusiasts cited 10 mg to 30 mg daily as the optimal dose for a minimum of 12 weeks which is 10 times higher than the clinically studied dose with anecdotal evidence suggesting that taking ostarine for much longer than this can suppress free T levels 1 a b c d e f g h i j k l m n o Dalton JT Barnette KG Bohl CE Hancock ML Rodriguez D Dodson ST et al September 2011 The selective androgen receptor modulator GTx 024 enobosarm improves lean body mass and physical function in healthy elderly men and postmenopausal women results of a double blind placebo controlled phase II trial Journal of Cachexia Sarcopenia and Muscle 2 3 153 161 doi 10 1007 s13539 011 0034 6 PMC 3177038 PMID 22031847 The reductions in SHBG with enobosarm in men and women 61 and 80 respectively at the 3 mg dose exceed those observed in men treated with a 600 mg intramuscular testosterone enanthate 31 41 Bhasin S Storer TW Berman N Callegari C Clevenger B Phillips J et al July 1996 The effects of supraphysiologic doses of testosterone on muscle size and strength in normal men The New England Journal of Medicine 335 1 1 7 doi 10 1056 NEJM199607043350101 PMID 8637535 Coss CC Jones A Hancock ML Steiner MS Dalton JT 2014 Selective androgen receptor modulators for the treatment of late onset male hypogonadism Asian Journal of Andrology 16 2 256 261 doi 10 4103 1008 682X 122339 PMC 3955335 PMID 24407183 a b c d e f g h i j k Coss CC Jones A Dalton JT November 2014 Selective androgen receptor modulators as improved androgen therapy for advanced breast cancer Steroids 90 94 100 doi 10 1016 j steroids 2014 06 010 PMID 24945109 S2CID 23450056 a b c d Vignali JD Pak KC Beverley HR DeLuca JP Downs JW Kress AT et al May 2023 Systematic Review of Safety of Selective Androgen Receptor Modulators in Healthy Adults Implications for Recreational Users Journal of Xenobiotics 13 2 218 236 doi 10 3390 jox13020017 PMC 10204391 PMID 37218811 Bedi H Hammond C Sanders D Yang HM Yoshida EM January 2021 Drug Induced Liver Injury From Enobosarm Ostarine a Selective Androgen Receptor Modulator ACG Case Reports Journal 8 1 e00518 doi 10 14309 crj 0000000000000518 PMC 8337042 PMID 34368386 Weinblatt D Roy S May 2022 Drug Induced Liver Injury Secondary to Enobosarm A Selective Androgen Receptor Modulator Journal of Medical Cases 13 5 244 248 doi 10 14740 jmc3937 PMC 9119364 PMID 35655632 Mertens JE Bommer MT Regier MB Gabriels G Pavenstadt H Grunewald I et al October 2023 Liver Injury after Selective Androgen Receptor Modulator Intake A Case Report and Review of the Literature Zeitschrift Fur Gastroenterologie doi 10 1055 a 2165 6323 PMID 37871633 S2CID 264426934 Arayangkool C Gozun M Tanariyakul M Techasatian W Leesutipornchai T Nishimura Y July 2023 Bile Cast Nephropathy Because of Acute Liver Injury Associated With Selective Androgen Receptor Modulators ACG Case Reports Journal 10 7 e01105 doi 10 14309 crj 0000000000001105 PMC 10371315 PMID 37501938 a b c d e f g h Kicman AT June 2008 Pharmacology of anabolic steroids British Journal of Pharmacology 154 3 502 521 doi 10 1038 bjp 2008 165 PMC 2439524 PMID 18500378 Liang JY Chang HC Hsu GL 2018 Penis Endocrinology In Skinner MK ed Encyclopedia of Reproduction Elsevier Science p 376 ISBN 978 0 12 815145 7 Retrieved 23 December 2023 Handelsman DJ July 2022 History of androgens and androgen action Best Practice amp Research Clinical Endocrinology amp Metabolism 36 4 101629 doi 10 1016 j beem 2022 101629 PMID 35277356 The next invention was that of the first non steroidal androgen by Dalton et al 111 in 1998 six decades after the first non steroidal estrogen 112 This creates a new class of non steroidal synthetic androgen often termed Specific Androgen Receptor Modulators SARM a misleading marketing term rather than an accurate pharmacological description 113 114 usurping a speculative but unsound analogy with Specific Estrogen Receptor Modulators SERM none of the non steroidal androgens under development 116 117 are marketed by 2021 Yet hope springs eternal for this new attempt to separate anabolic from androgenic properties of androgens to facilitate marketing for muscle wasting and other selective effects of testosterone Handelsman DJ May 2011 Commentary androgens and anabolic steroids the one headed janus Endocrinology 152 5 1752 1754 doi 10 1210 en 2010 1501 PMID 21511988 Although development of the first nonsteroidal androgens 17 18 as candidate selective AR modulators 19 raises hope of resurrecting this defunct term 20 prereceptor activation mechanisms cannot apply to nonsteroidal androgens and the singular AR lacks a dual drive mechanism of the other paired sex steroid receptors Consequently it is not surprising that available knowledge 21 provides only slender hope that this failed and probably false dichotomy will now succeed through a renewed search guided by the same in vivo bioassay FDA In Brief FDA warns against using SARMs in body building products Retrieved 1 August 2019 a b Lim E Tarulli G Portman N Hickey TE Tilley WD Palmieri C December 2016 Pushing estrogen receptor around in breast cancer Endocrine Related Cancer 23 12 T227 T241 doi 10 1530 ERC 16 0427 PMID 27729416 a b c d Kassem L Shohdy KS Makady NF Salem DS Ebrahim N Eldaly M 2019 11 16 Efficacy and Safety of Targeting Androgen Receptor in Advanced Breast Cancer A Systematic Review Current Cancer Therapy Reviews 15 3 197 206 doi 10 2174 1573394714666180821145032 S2CID 58234934 It is worth noting that SARMs were initially developed to get benefit of their anabolic effect on muscle and bone without much harm to other tissues One randomized controlled trial 28 recruited male and females with cancer and weight loss showed that enobosarm 1 mg or 3 mg was associated with significant increase in lean body mass compared to placebo This led to another ongoing trial with more selection aiming to evaluate enobosarm with higher doses 9 or 18 mg effect on physical function and lean body mass of ER AR breast cancer patients NCT02463032 Such additional action of this class of drugs carries major hope for patients with AR positive advanced breast cancer where weight loss muscle weakness and physical inactivity represent a big challenge for the patient s quality of life QOL a b c Hackbart H Cui X Lee JS October 2023 Androgen receptor in breast cancer and its clinical implication Translational Breast Cancer Research 4 30 doi 10 21037 tbcr 23 44 PMC 10632549 PMID 37946721 a b c Ma J Chan JJ Toh CH Yap YS September 2023 Emerging systemic therapy options beyond CDK4 6 inhibitors for hormone receptor positive HER2 negative advanced breast cancer npj Breast Cancer 9 1 74 doi 10 1038 s41523 023 00578 3 PMC 10491615 PMID 37684290 a b c d e f Thevis M Kuuranne T Geyer H Schanzer W January 2017 Annual banned substance review analytical approaches in human sports drug testing Drug Testing and Analysis 9 1 6 29 doi 10 1002 dta 2139 PMID 27885819 New information on elimination kinetics and potential drug drug interactions of the SARM GTx 024 Enobosarm Ostarine S 22 MK 2866 was presented by Coss et al indicating maximum plasma concentrations of the intact drug and its glucuronic acid conjugate of ca 60 and 100 ng mL respectively reached between 1 and 2 h following an oral dose of 3 mg 85 The CYP3A4 inhibitor itraconazole did not affect pharmacokinetic parameters of GTx 024 while the CYP3A4 inducer rifampin reduced maximum plasma concentrations significantly Conversely the UGT inhibitor probenecid increased levels of both GTx 024 and its glucuronide a b c d e f g Zhang X Sui Z February 2013 Deciphering the selective androgen receptor modulators paradigm Expert Opinion on Drug Discovery 8 2 191 218 doi 10 1517 17460441 2013 741582 PMID 23231475 S2CID 2584722 The structure and name of Ostarine GTx 024 MK 2866 Enobosarm S 22 were disclosed by the USAN Council in November 2011 to establish it as a first member of a new class of drugs furthest in clinical development Structure 2 in Scheme 1 a b c d e Kim J Wu D Hwang DJ Miller DD Dalton JT October 2005 The para substituent of S 3 phenoxy 2 hydroxy 2 methyl N 4 nitro 3 trifluoromethyl phenyl propionamides is a major structural determinant of in vivo disposition and activity of selective androgen receptor modulators The Journal of Pharmacology and Experimental Therapeutics 315 1 230 239 doi 10 1124 jpet 105 088344 PMID 15987833 S2CID 30799845 a b c d e f Jones A Hwang DJ Duke CB He Y Siddam A Miller DD et al August 2010 Nonsteroidal selective androgen receptor modulators enhance female sexual motivation J Pharmacol Exp Ther 334 2 439 48 doi 10 1124 jpet 110 168880 PMC 2913771 PMID 20444881 Miner JN Chang W Chapman MS Finn PD Hong MH Lopez FJ et al January 2007 An orally active selective androgen receptor modulator is efficacious on bone muscle and sex function with reduced impact on prostate Endocrinology 148 1 363 73 doi 10 1210 en 2006 0793 PMID 17023534 a b c d e f Narayanan R Coss CC Dalton JT April 2018 Development of selective androgen receptor modulators SARMs Molecular and Cellular Endocrinology 465 134 142 doi 10 1016 j mce 2017 06 013 PMC 5896569 PMID 28624515 a b Gao W Dalton JT February 2007 Ockham s razor and selective androgen receptor modulators SARMs are we overlooking the role of 5alpha reductase Molecular Interventions 7 1 10 13 doi 10 1124 mi 7 1 3 PMC 2040232 PMID 17339601 a b Bhasin S Jasuja R May 2009 Selective androgen receptor modulators as function promoting therapies Current Opinion in Clinical Nutrition and Metabolic Care 12 3 232 240 doi 10 1097 MCO 0b013e32832a3d79 PMC 2907129 PMID 19357508 At the doses that have been tested the first generation SARMs induce modest gains in lean body mass in healthy volunteers which are nowhere near the much greater gains in skeletal muscle mass reported with supraphysiological doses of testosterone The modest gains of 1 0 to 1 5 kg in fat free mass with first generation SARMs over 4 6 weeks should be contrasted with the 5 7 kg gains in fat free mass with 300 and 600 mg doses of testosterone enanthate However it is possible that next generation of SARM molecules will have greater potency and selectivity than the first generation SARMs Hohl A Marcelli M 2023 Androgen Receptor in Health and Disease In Hohl A ed Testosterone Cham Springer International Publishing pp 21 75 doi 10 1007 978 3 031 31501 5 2 ISBN 978 3 031 31500 8 Physiologically N C interaction is indispensable because it delays ligand dissociation from the receptor protects the ligand binding pocket and prevents receptor degradation 118 That N C interaction is essential in AR physiology is demonstrated by the identification of AR LBD mutations resulting in androgen insensitivity syndromes AIS that disrupt N C interaction without affecting the equilibrium binding affinity for the ligand 119 120 He B Wilson EM April 2002 The NH 2 terminal and carboxyl terminal interaction in the human androgen receptor Mol Genet Metab 75 4 293 8 doi 10 1016 S1096 7192 02 00009 4 PMID 12051960 a b Dalton JT Taylor RP Mohler ML Steiner MS December 2013 Selective androgen receptor modulators for the prevention and treatment of muscle wasting associated with cancer Current Opinion in Supportive and Palliative Care 7 4 345 351 doi 10 1097 SPC 0000000000000015 PMID 24189892 S2CID 35120033 Enobosarm was discovered in 2004 as a hyper myoanabolic SARM that dissociated the anabolic from androgenic effects of AR in terms of potency ED50 and efficacy Emax 29 Levator ani muscle weight was increased to 131 and 136 of intact controls in intact and castrated maintenance mode rats respectively without significant increases in ventral prostate and seminal vesicles weights Importantly increases in levator ani muscle weight were associated with increases in muscle strength soleus in rats Enobosarm also exerted in vivo osteoanabolic effects alone and synergistically with alendronate in terms of bone density strength and structure 30 which was explained by in vitro mechanistic studies that demonstrated antiresorptive osteoclast inhibition and anabolic osteoblast differentiation effects 31 Dubois V Simitsidellis I Laurent MR Jardi F Saunders PT Vanderschueren D et al December 2015 Enobosarm GTx 024 Modulates Adult Skeletal Muscle Mass Independently of the Androgen Receptor in the Satellite Cell Lineage Endocrinology 156 12 4522 4533 doi 10 1210 en 2015 1479 hdl 20 500 11820 072a494a dfdc 4785 8f77 1a4e7e40e07a PMID 26393303 a b Narayanan R Coss CC Yepuru M Kearbey JD Miller DD Dalton JT November 2008 Steroidal androgens and nonsteroidal tissue selective androgen receptor modulator S 22 regulate androgen receptor function through distinct genomic and nongenomic signaling pathways Molecular Endocrinology 22 11 2448 2465 doi 10 1210 me 2008 0160 PMID 18801930 Xie Y Tian Y Zhang Y Zhang Z Chen R Li M et al February 2022 Overview of the development of selective androgen receptor modulators SARMs as pharmacological treatment for osteoporosis 1998 2021 European Journal of Medicinal Chemistry 230 114119 doi 10 1016 j ejmech 2022 114119 PMID 35063736 S2CID 245941791 Similar to other N arylpropionamide SARMs in male rats treated for 14 days at 1 mg day dose S 22 17 exhibited increased levator ani muscle weight but significantly reduced prostate weight Le Rademacher JG Crawford J Evans WJ Jatoi A September 2017 Overcoming obstacles in the design of cancer anorexia weight loss trials Critical Reviews in Oncology Hematology 117 30 37 doi 10 1016 j critrevonc 2017 06 008 PMC 5561667 PMID 28807233 Lambert CP June 2021 Should the FDA s criteria for the clinical efficacy of cachexia drugs be changed Is Ostarine safe and effective Journal of Cachexia Sarcopenia and Muscle 12 3 531 532 doi 10 1002 jcsm 12695 PMC 8200429 PMID 33759397 Ramage MI Skipworth RJ December 2018 The relationship between muscle mass and function in cancer cachexia smoke and mirrors Current Opinion in Supportive and Palliative Care 12 4 439 444 doi 10 1097 SPC 0000000000000381 hdl 20 500 11820 2b90be5b 7682 4681 a85d 101d3abe3ed9 PMID 30138131 Brooks A Schumpp A Dawson J Andriello E Fairman CM 2023 Considerations for designing trials targeting muscle dysfunction in exercise oncology Frontiers in Physiology 14 1120223 doi 10 3389 fphys 2023 1120223 PMC 9972098 PMID 36866171 Bhasin S Woodhouse L Casaburi R Singh AB Bhasin D Berman N et al December 2001 Testosterone dose response relationships in healthy young men American Journal of Physiology Endocrinology and Metabolism 281 6 E1172 E1181 doi 10 1152 ajpendo 2001 281 6 E1172 PMID 11701431 S2CID 2344757 The administration of the GnRH agonist plus graded doses of testosterone resulted in mean nadir testosterone concentrations of 253 306 542 1 345 and 2 370 ng dl at the 25 50 125 300 and 600 mg doses respectively Fat free mass increased dose dependently in men receiving 125 300 or 600 mg of testosterone weekly change 3 4 5 2 and 7 9 kg respectively The changes in fat free mass were highly dependent on testosterone dose P 0 0001 and correlated with log testosterone concentrations r 0 73 P 0 0001 Pan MM Kovac JR April 2016 Beyond testosterone cypionate evidence behind the use of nandrolone in male health and wellness Transl Androl Urol 5 2 213 9 doi 10 21037 tau 2016 03 03 PMC 4837307 PMID 27141449 Bond P Smit DL de Ronde W 2022 Anabolic androgenic steroids How do they work and what are the risks Frontiers in Endocrinology 13 1059473 doi 10 3389 fendo 2022 1059473 PMC 9837614 PMID 36644692 Anabolic androgenic steroids AAS are a class of natural and synthetic hormones that owe their name to their chemical structure the steroid nucleus see Figure 1 and the biological effects anabolic and androgenic they induce Anabolic refers to the skeletal muscle building properties of AAS whereas androgenic refers to the induction and maintenance of male secondary sexual characteristics which in principle includes the anabolic action thereby rendering the term an oxymoron 1 Basaria S Collins L Dillon EL Orwoll K Storer TW Miciek R et al January 2013 The safety pharmacokinetics and effects of LGD 4033 a novel nonsteroidal oral selective androgen receptor modulator in healthy young men The Journals of Gerontology Series A Biological Sciences and Medical Sciences 68 1 87 95 doi 10 1093 gerona gls078 PMC 4111291 PMID 22459616 Alen M Rahkila P December 1988 Anabolic androgenic steroid effects on endocrinology and lipid metabolism in athletes Sports Medicine 6 6 327 332 doi 10 2165 00007256 198806060 00001 PMID 3068771 S2CID 37898289 Sinnecker G Kohler S June 1989 Sex hormone binding globulin response to the anabolic steroid stanozolol evidence for its suitability as a biological androgen sensitivity test The Journal of Clinical Endocrinology and Metabolism 68 6 1195 1200 doi 10 1210 jcem 68 6 1195 PMID 2723028 Eisenfeld AJ Aten RF 1987 Estrogen receptors and androgen receptors in the mammalian liver Journal of Steroid Biochemistry 27 4 6 1109 1118 doi 10 1016 0022 4731 87 90197 x PMID 3320548 Parenteral routes of sex steroid administration Liver effects could also be diminished by using routes of administration other than oral First pass effects would be avoided Although this discussion has focused predominantly on contraceptives similar principles seem applicable for diminishing the liver side effects of androgenic preparations Thus androgens should be selected which are likely to be metabolized on entering the hepatocyte and a parenteral route of administration may be preferable Androgens which are not 17 alkylated might produce fewer liver side effects than 17 alkylated derivatives judging from their relative effects on plasma protein levels Z Lax ER 1987 Mechanisms of physiological and pharmacological sex hormone action on the mammalian liver Journal of Steroid Biochemistry 27 4 6 1119 1128 doi 10 1016 0022 4731 87 90198 1 PMID 3320549 Androgen and oestrogen receptors have been demonstrated in mammalian liver but since it is generally accepted that they are probably non functional at endogenous steroid concentrations it is not apparent how they mediate physiological influences on this organ Nor is it certain to what extent pharmacological actions of sex hormones reflect overstimulation of physiological routes or whether alternative mechanisms become available once threshold values have been reached Many of the dangers inherent in synthetic androgen or anabolic steroid therapy may be due less to the androgenic characteristics than to the structural modifications performed to prevent hepatic inactivation e g insertion of an acetylene group at 17a a b Enobosarm PubChem U S National Library of Medicine a b Enobosarm DrugBank a b Cleve A Fritzemeier KH Haendler B Heinrich N Moller C Schwede W et al 2013 Pharmacology and Clinical Use of Sex Steroid Hormone Receptor Modulators Sex and Gender Differences in Pharmacology Handbook of Experimental Pharmacology Vol 214 pp 543 587 doi 10 1007 978 3 642 30726 3 24 ISBN 978 3 642 30725 6 PMID 23027466 Both male androgens and female oestrogens progestins sex hormones are steroid hormones these compounds have several properties in common they are small very lipophilic molecules with the potential to freely diffuse through cell membranes Their receptors also share important features in all animals the receptors for steroid hormones are part of the nuclear receptor superfamily of ligand triggered transcription factors Mangelsdorf et al 1995 Unlike membrane receptors that trigger intracellular signalling pathways these receptors work by influencing gene expression in the cell a b Yoon JH Kwon KS June 2021 Receptor Mediated Muscle Homeostasis as a Target for Sarcopenia Therapeutics Endocrinology and Metabolism 36 3 478 490 doi 10 3803 EnM 2021 1081 PMC 8258343 PMID 34218646 Intracellular receptors account for 10 to 15 of drugs on the market including drugs that act on cytoplasmic receptors such as androgen receptors ARs estrogen receptors progesterone receptors and glucocorticoid receptors and other drugs that act on nuclear receptors such as vitamin D receptor VDR thyroid hormone receptors and peroxisome proliferator activated receptors 27 30 Ligands of intracellular receptors include lipophilic vitamins steroid hormones and small chemicals such as hydrogen peroxide and nitric oxide which require membrane permeability for intracellular delivery 30 31 There are several barriers to the intracellular delivery of therapeutic drugs such as lysosome degradation and active efflux out of the cell Lowmolecular weight lipophilic compounds can diffuse directly into cells whereas high molecular weight compounds usually need membrane transporters or endocytosis 32 33 Proper entry into the cell and subsequent contact with the exact target lead to better therapeutic effects and reduce undesirable adverse effects 34 Mohd Fauzi F Koutsoukas A Cunningham A Gallegos A Sedefov R Bender A July 2013 Computer aided in silico approaches in the mode of action analysis and safety assessment of ostarine and 4 methylamphetamine Human Psychopharmacology 28 4 365 378 doi 10 1002 hup 2322 PMID 23881885 S2CID 22800581 Gao W Bohl CE Dalton JT September 2005 Chemistry and structural biology of androgen receptor Chemical Reviews 105 9 3352 3370 doi 10 1021 cr020456u PMC 2096617 PMID 16159155 a b Chen J Kim J Dalton JT June 2005 Discovery and therapeutic promise of selective androgen receptor modulators Molecular Interventions 5 3 173 188 doi 10 1124 mi 5 3 7 PMC 2072877 PMID 15994457 a b Hwang DJ He Y Ponnusamy S Mohler ML Thiyagarajan T McEwan IJ et al January 2019 New Generation of Selective Androgen Receptor Degraders Our Initial Design Synthesis and Biological Evaluation of New Compounds with Enzalutamide Resistant Prostate Cancer Activity Journal of Medicinal Chemistry 62 2 491 511 doi 10 1021 acs jmedchem 8b00973 hdl 2164 13357 PMID 30525603 S2CID 54472127 Corona G Rastrelli G Vignozzi L Maggi M June 2012 Emerging medication for the treatment of male hypogonadism Expert Opinion on Emerging Drugs 17 2 239 259 doi 10 1517 14728214 2012 683411 PMID 22612692 S2CID 22068249 Holderbaum A April 2020 Emerging anabolic drugs investigation of the in vitro and in vivo metabolism of selective androgen receptor modulators PDF Ph D thesis United Kingdom Queen s University Belfast Ricci F Buzzatti G Rubagotti A Boccardo F November 2014 Safety of antiandrogen therapy for treating prostate cancer Expert Opinion on Drug Safety 13 11 1483 1499 doi 10 1517 14740338 2014 966686 PMID 25270521 S2CID 207488100 Bone sparing effects of antiandrogen monotherapy might be due to selective AR modulators tissue specific and androgen responsive not affected by antiandrogen therapy resulting in testosterone still being active in bone during non steroidal antiandrogen administration 90 Allan G Lai MT Sbriscia T Linton O Haynes Johnson D Bhattacharjee S et al January 2007 A selective androgen receptor modulator that reduces prostate tumor size and prevents orchidectomy induced bone loss in rats The Journal of Steroid Biochemistry and Molecular Biology 103 1 76 83 doi 10 1016 j jsbmb 2006 07 006 PMID 17049844 S2CID 25283876 Wadhwa VK Weston R Parr NJ June 2011 Bicalutamide monotherapy preserves bone mineral density muscle strength and has significant health related quality of life benefits for osteoporotic men with prostate cancer BJU International 107 12 1923 1929 doi 10 1111 j 1464 410X 2010 09726 x PMID 20950306 S2CID 205543615 a b Mohler ML Bohl CE Jones A Coss CC Narayanan R He Y et al June 2009 Nonsteroidal selective androgen receptor modulators SARMs dissociating the anabolic and androgenic activities of the androgen receptor for therapeutic benefit Journal of Medicinal Chemistry 52 12 3597 3617 doi 10 1021 jm900280m PMID 19432422 Readers are cautioned to note that the name Ostarine is often mistakenly linked to the chemical structure of 8 which is also known as andarine The chemical structure of Ostarine has not been publicly disclosed The authors are unable to provide additional information Dart DA Kandil S Tommasini Ghelfi S Serrano de Almeida G Bevan CL Jiang W et al September 2018 Novel Trifluoromethylated Enobosarm Analogues with Potent Antiandrogenic Activity In Vitro and Tissue Selectivity In Vivo Molecular Cancer Therapeutics 17 9 1846 1858 doi 10 1158 1535 7163 MCT 18 0037 PMID 29895558 Pertusati F Ferla S Bassetto M Brancale A Khandil S Westwell AD et al October 2019 A new series of bicalutamide enzalutamide and enobosarm derivatives carrying pentafluorosulfanyl SF5 and pentafluoroethyl C2F5 substituents Improved antiproliferative agents against prostate cancer European Journal of Medicinal Chemistry 180 1 14 doi 10 1016 j ejmech 2019 07 001 PMID 31288149 S2CID 195872311 a b Dalton JT Mukherjee A Zhu Z Kirkovsky L Miller DD March 1998 Discovery of nonsteroidal androgens Biochemical and Biophysical Research Communications 244 1 1 4 doi 10 1006 bbrc 1998 8209 PMID 9514878 a b c d WO 2005120483 Dalton JT Mille DD Veverka KA Selective androgen receptor modulators and methods of use thereof published 22 December 2005 assigned to University of Tennessee Research Foundation a b Negro Vilar A October 1999 Selective androgen receptor modulators SARMs a novel approach to androgen therapy for the new millennium The Journal of Clinical Endocrinology and Metabolism 84 10 3459 3462 doi 10 1210 jcem 84 10 6122 PMID 10522980 He Y Yin D Perera M Kirkovsky L Stourman N Li W et al August 2002 Novel nonsteroidal ligands with high binding affinity and potent functional activity for the androgen receptor European Journal of Medicinal Chemistry 37 8 619 634 doi 10 1016 s0223 5234 02 01335 1 PMID 12161060 a b Yin D Gao W Kearbey JD Xu H Chung K He Y et al March 2003 Pharmacodynamics of selective androgen receptor modulators The Journal of Pharmacology and Experimental Therapeutics 304 3 1334 1340 doi 10 1124 jpet 102 040840 PMID 12604714 S2CID 14724811 Perera MA 2003 The pharmacology pharmacokinetics and metabolism of a novel nonsteroidal selective androgen receptor modulator Thesis OCLC 56700020 ProQuest 305301414 page needed Nagle M 7 November 2007 Merck flexes muscle with GTx deal Outsourcing Pharma Swanekamp K 15 March 2010 Merck And GTx Go Their Separate Ways Forbes Enobosarm fails endpoints in Ph III study The Pharma Letter 20 August 2013 Sheffield M April 4 2014 Steiner resigns from GTx Memphis Business Journal Garde D 4 April 2014 GTx s CEO finds the door as the company moves on from a PhIII failure FierceBiotech GTx begins Phase II trial of enobosarm to treat women with stress urinary incontinence Drug Development Technology 14 January 2016 Archived from the original on 22 June 2018 GTx s Enobosarm Fails Phase II Trial in Stress Urinary Incontinence Stock Plunges 90 Genetic Engineering amp Biotechnology News 21 September 2018 Retrieved 1 August 2019 Pelosci A 10 January 2022 FDA Grants Fast Track Designation to Enobosarm in AR ER HER2 Metastatic Breast Cancer Cancer Network Retrieved 27 August 2023 Recommended INN List 69 International Nonproprietary Names for Pharmaceutical Substances INN PDF WHO Drug Information 27 1 2013 Enobosarm 2S 3 4 cyanophenoxy N 4 cyano 3 trifluoromethyl phenyl 2 hydroxy 2 methylpropanamide Thevis M Kohler M Schlorer N Kamber M Kuhn A Linscheid MW et al May 2008 Mass spectrometry of hydantoin derived selective androgen receptor modulators Journal of Mass Spectrometry 43 5 639 650 Bibcode 2008JMSp 43 639T doi 10 1002 jms 1364 PMID 18095383 Thevis M Kohler M Thomas A Maurer J Schlorer N Kamber M et al May 2008 Determination of benzimidazole and bicyclic hydantoin derived selective androgen receptor antagonists and agonists in human urine using LC MS MS Analytical and Bioanalytical Chemistry 391 1 251 261 doi 10 1007 s00216 008 1882 6 PMID 18270691 S2CID 206899531 Dynamic Technical Formulations LLC Issues a Voluntary Nationwide Recall of Tri Ton Due to the Presence of Andarine and Ostarine U S Food amp Drug Administration May 19 2017 Raimondi M January 22 2020 NSAC Sean O Malley can fight at UFC 248 in March after serving suspension ESPN Retrieved June 9 2020 Needelman J 14 September 2020 Clemson lineman suspended by ncaa for positive ostarine test opens up for first time Retrieved November 13 2020 Bieler D 25 July 2019 Failed PED test has a highly paid offensive lineman sharing polygraph results Washington Post Retrieved 25 July 2019 One of the NFL s highest paid offensive linemen claimed Wednesday that he did not knowingly take a banned substance he says got him a four game suspension and he took a polygraph test in an attempt to prove it UCI statement concerning Matteo Spreafico Press release Union Cycliste Internationale 4 May 2021 Tandara e suspensa por potencial violacao do antidoping e esta fora das Olimpiadas Tandara is suspended for potential anti doping violation and is out of the Olympics globo com in Portuguese 6 August 2021 Tokyo Olympics Team GB 4x100m relay silver medallist CJ Ujah suspended for suspected doping violation Sky News 12 August 2021 CJ Ujah Great Britain lose Tokyo Olympics relay medal after doping violation BBC 18 February 2022 Public Disclosure of Disposition of Anti Doping Matter Under Rule 14 3 2 Chijindu Ujah GBR PDF Athletics Integrity Unit 10 October 2022 29 September 2022 In the Matter of the Horse Racing License Act 2015 S 0 2015 C 38 Sched 9 And in the Matter of Robert Gerl PDF Retrieved 2 June 2022 Cardinals WR DeAndre Hopkins still hopes to reduce six game suspension NFL com 23 June 2022 Amir Khan banned for two years after anti doping test reveals presence of prohibited substance BBC co uk 4 April 2023 1 Further reading editCrawford J Prado CM Johnston MA Gralla RJ Taylor RP Hancock ML et al June 2016 Study Design and Rationale for the Phase 3 Clinical Development Program of Enobosarm a Selective Androgen Receptor Modulator for the Prevention and Treatment of Muscle Wasting in Cancer Patients POWER Trials Current Oncology Reports 18 6 37 doi 10 1007 s11912 016 0522 0 PMC 4853438 PMID 27138015 External links editEnobosarm GTx 024 MK 2866 Ostarine S 22 VERU 024 Veru Healthcare AdisInsight Boxer Garcia tests positive for banned substance ESPN com 2024 05 02 Retrieved 2024 05 02 Retrieved from https en wikipedia org w index php title Enobosarm amp oldid 1221809326, wikipedia, wiki, book, books, library,

article

, read, download, free, free download, mp3, video, mp4, 3gp, jpg, jpeg, gif, png, picture, music, song, movie, book, game, games.