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Alpha-adrenergic agonist

March 06, 2023

Alpha-adrenergic agonists are a class of sympathomimetic agents that selectively stimulates alpha adrenergic receptors. The alpha-adrenergic receptor has two subclasses α1 and α2. Alpha 2 receptors are associated with sympatholytic properties. Alpha-adrenergic agonists have the opposite function of alpha blockers. Alpha adrenoreceptor ligands mimic the action of epinephrine and norepinephrine signaling in the heart, smooth muscle and central nervous system, with norepinephrine being the highest affinity. The activation of α1 stimulates the membrane bound enzyme phospholipase C, and activation of α2 inhibits the enzyme adenylate cyclase. Inactivation of adenylate cyclase in turn leads to the inactivation of the secondary messenger cyclic adenosine monophosphate and induces smooth muscle and blood vessel constriction.

Alpha adrenergic agonist
Drug class
Skeletal structor formula of phenylephrine, a common nasal decongestant
Class identifiers
UseDecongestant, Hypotension, Bradycardia, Hypothermia etc.
ATC codeN07
Biological targetAlpha adrenergic receptors of the α subtype
External links
MeSHD000316
In Wikidata

Classes

 
Norepinephrine (noradrenaline)

Although complete selectivity between receptor agonism is rarely achieved, some agents have partial selectivity. NB: the inclusion of a drug in each category just indicates the activity of the drug at that receptor, not necessarily the selectivity of the drug (unless otherwise noted).

α1 agonist

Main article: Alpha-1 adrenergic receptor § agonist

α1 agonist: stimulates phospholipase C activity. (vasoconstriction and mydriasis; used as vasopressors, nasal decongestants and during eye exams). Selected examples are:

α2 agonist

Main article: Alpha-2 adrenergic receptor § Agonists

α2 agonist: inhibits adenylyl cyclase activity, reduces brainstem vasomotor center-mediated CNS activation; used as antihypertensive, sedative & treatment of opiate dependence and alcohol withdrawal symptoms). Selected examples are:

Nonspecific agonist

Nonspecific agonists act as agonists at both alpha-1 and alpha-2 receptors.

Undetermined/unsorted

The following agents are also listed as agonists by MeSH.[16]

Clinical significance

Alpha-adrenergic agonists, more specifically the auto receptors of alpha 2 neurons, are used in the treatment of glaucoma by decreasing the production of aqueous fluid by the ciliary bodies of the eye and also by increasing uveoscleral outflow. Medications such as clonidine and dexmedetomidine target pre-synaptic auto receptors, therefore leading to an overall decrease in norepinephrine which clinically can cause effects such as sedation, analgesia, lowering of blood pressure and bradycardia. There is also low quality evidence that they can reduce shivering post operatively[17]

The reduction of the stress response caused by alpha 2 agonists were theorised to be beneficial peri operatively by reducing cardiac complications, however this has shown not to be clinically effective as there was no reduction in cardiac events or mortality but there was an increased incidence of hypotension and bradycardia[18]

See also

References

  1. ^ Declerck I, Himpens B, Droogmans G, Casteels R (September 1990). "The alpha 1-agonist phenylephrine inhibits voltage-gated Ca2(+)-channels in vascular smooth muscle cells of rabbit ear artery". Pflügers Arch. 417 (1): 117–9. doi:10.1007/BF00370780. PMID 1963492. S2CID 8074029.
  2. ^ MacLean MR, Thomson M, Hiley CR (June 1989). "Pressor effects of the alpha 2-adrenoceptor agonist B-HT 933 in anaesthetized and haemorrhagic rats: comparison with the haemodynamic effects of amidephrine". Br. J. Pharmacol. 97 (2): 419–32. doi:10.1111/j.1476-5381.1989.tb11969.x. PMC 1854522. PMID 2569342.
  3. ^ Sagvolden T (2006). "The alpha-2A adrenoceptor agonist guanfacine improves sustained attention and reduces overactivity and impulsiveness in an animal model of Attention-Deficit/Hyperactivity Disorder (ADHD)". Behav Brain Funct. 2: 41. doi:10.1186/1744-9081-2-41. PMC 1764416. PMID 17173664.
  4. ^ Atalik KE, Sahin AS, Doğan N (April 2000). "Interactions between phenylephrine, clonidine and xylazine in rat and rabbit aortas". Methods Find Exp Clin Pharmacol. 22 (3): 145–7. PMID 10893695.
  5. ^ Lemke KA (2004). "Perioperative use of selective alpha-2 agonists and antagonists in small animals". Can. Vet. J. 45 (6): 475–80. PMC 548630. PMID 15283516.
  6. ^ Crassous PA, Cardinaletti C, Carrieri A, Bruni B, Di Vaira M, Gentili F, Ghelfi F, Giannella M, Paris H, Piergentili A, Quaglia W, Schaak S, Vesprini C, Pigini M (August 2007). "Alpha2-adrenoreceptors profile modulation. 3.1 (R)-(+)-m-nitrobiphenyline, a new efficient and alpha2C-subtype selective agonist". Journal of Medicinal Chemistry. 50 (16): 3964–8. doi:10.1021/jm061487a. PMID 17630725.
  7. ^ Del Bello, Fabio; Mattioli, Laura; Ghelfi, Francesca; Giannella, Mario; Piergentili, Alessandro; Quaglia, Wilma; Cardinaletti, Claudia; Perfumi, Marina; Thomas, Russell J.; Zanelli, Ugo; Marchioro, Carla; Dal Cin, Michele; Pigini, Maria (11 November 2010). "Fruitful Adrenergic α2C-Agonism/α2A-Antagonism Combination to Prevent and Contrast Morphine Tolerance and Dependence". Journal of Medicinal Chemistry. 53 (21): 7825–7835. doi:10.1021/jm100977d. PMID 20925410.
  8. ^ Hsu, W. H. and Lu, Z.-X. (1984). Amitraz' induced delay of gastrointestinal transit in mice: Mediated by α2 adrenergic receptors. Drug Development Research, Volume 4 (6), 655- 680.
  9. ^ "Press Announcements - FDA approves the first non-opioid treatment for management of opioid withdrawal symptoms in adults". www.fda.gov. Retrieved 18 May 2018.
  10. ^ Sinclair MD (November 2003). "A review of the physiological effects of alpha2-agonists related to the clinical use of medetomidine in small animal practice". Can. Vet. J. 44 (11): 885–97. PMC 385445. PMID 14664351.
  11. ^ Haenisch, B.; Walstab, J.; Herberhold, S.; Bootz, F.; Tschaikin, M.; Ramseger, R.; Bönisch, H. (2009). "Alpha-adrenoceptor Agonistic Activity of Oxymetazoline and Xylometazoline". Fundamental & Clinical Pharmacology. 24 (6): 729–39. doi:10.1111/j.1472-8206.2009.00805.x. PMID 20030735. S2CID 25064699.
  12. ^ Westfall Thomas C, Westfall David P, "Chapter 6. Neurotransmission: The Autonomic and Somatic Motor Nervous Systems" (Chapter). Brunton LL, Lazo JS, Parker KL: Goodman & Gilman's The Pharmacological Basis of Therapeutics, 11e: . Archived from the original on 2011-09-30. Retrieved 2015-01-24..
  13. ^ Horie, K; Obika, K; Foglar, R (1995). "Selectivity of the imidazoline α-adrenoceptor agonists (oxymetazoline and cirazoline) for human cloned α1-adrenoceptor subtypes". British Journal of Pharmacology. 116 (1): 1611–8. doi:10.1111/j.1476-5381.1995.tb16381.x. PMC 1908909. PMID 8564227.
  14. ^ Ruffolo, R. R. Jr.; Waddell, J. E. (1982). "Receptor interactions of imidazolines. IX. Cirazoline is an α1 adrenergic agonist and an α2 adrenergic antagonist". Journal of Pharmacology and Experimental Therapeutics. 222 (1): 29–36. PMID 6123592.
  15. ^ Shen, Howard (2008). Illustrated Pharmacology Memory Cards: PharMnemonics. Minireview. p. 4. ISBN 978-1-59541-101-3.
  16. ^ MeSH list of agents 82000316
  17. ^ Lewis, Sharon R; Nicholson, Amanda; Smith, Andrew F; Alderson, Phil (2015-08-10). "Alpha-2 adrenergic agonists for the prevention of shivering following general anaesthesia". Cochrane Database of Systematic Reviews. 2015 (8): CD011107. doi:10.1002/14651858.cd011107.pub2. ISSN 1465-1858. PMC 9221859. PMID 26256531.
  18. ^ Duncan, Dallas; Sankar, Ashwin; Beattie, W Scott; Wijeysundera, Duminda N (2018-03-06). "Alpha-2 adrenergic agonists for the prevention of cardiac complications among adults undergoing surgery". Cochrane Database of Systematic Reviews. 2018 (3): CD004126. doi:10.1002/14651858.cd004126.pub3. ISSN 1465-1858. PMC 6494272. PMID 29509957.

External links

  •   Media related to Alpha-adrenergic agonists at Wikimedia Commons
  • Adrenergic+alpha-Agonists at the US National Library of Medicine Medical Subject Headings (MeSH)

March 06, 2023
alpha, adrenergic, agonist, class, sympathomimetic, agents, that, selectively, stimulates, alpha, adrenergic, receptors, alpha, adrenergic, receptor, subclasses, alpha, receptors, associated, with, sympatholytic, properties, have, opposite, function, alpha, bl. Alpha adrenergic agonists are a class of sympathomimetic agents that selectively stimulates alpha adrenergic receptors The alpha adrenergic receptor has two subclasses a1 and a2 Alpha 2 receptors are associated with sympatholytic properties Alpha adrenergic agonists have the opposite function of alpha blockers Alpha adrenoreceptor ligands mimic the action of epinephrine and norepinephrine signaling in the heart smooth muscle and central nervous system with norepinephrine being the highest affinity The activation of a1 stimulates the membrane bound enzyme phospholipase C and activation of a2 inhibits the enzyme adenylate cyclase Inactivation of adenylate cyclase in turn leads to the inactivation of the secondary messenger cyclic adenosine monophosphate and induces smooth muscle and blood vessel constriction Alpha adrenergic agonistDrug classSkeletal structor formula of phenylephrine a common nasal decongestantClass identifiersUseDecongestant Hypotension Bradycardia Hypothermia etc ATC codeN07Biological targetAlpha adrenergic receptors of the a subtypeExternal linksMeSHD000316In Wikidata Contents 1 Classes 1 1 a1 agonist 1 2 a2 agonist 1 3 Nonspecific agonist 1 4 Undetermined unsorted 2 Clinical significance 3 See also 4 References 5 External linksClasses Edit Norepinephrine noradrenaline Although complete selectivity between receptor agonism is rarely achieved some agents have partial selectivity NB the inclusion of a drug in each category just indicates the activity of the drug at that receptor not necessarily the selectivity of the drug unless otherwise noted a1 agonist Edit Main article Alpha 1 adrenergic receptor agonist a1 agonist stimulates phospholipase C activity vasoconstriction and mydriasis used as vasopressors nasal decongestants and during eye exams Selected examples are Methoxamine Midodrine Metaraminol Phenylephrine 1 Amidephrine 2 Sdz nvi 085 104195 17 7 a2 agonist Edit Main article Alpha 2 adrenergic receptor Agonists a2 agonist inhibits adenylyl cyclase activity reduces brainstem vasomotor center mediated CNS activation used as antihypertensive sedative amp treatment of opiate dependence and alcohol withdrawal symptoms Selected examples are Clonidine mixed alpha2 adrenergic and imidazoline I1 receptor agonist Dexmedetomidine Fadolmidine Guanfacine 3 preference for alpha2A subtype of adrenoceptor Guanabenz most selective agonist for alpha2 adrenergic as opposed to imidazoline I1 Guanoxabenz metabolite of guanabenz Guanethidine peripheral alpha2 receptor agonist Xylazine 4 Tizanidine Methyldopa Methylnorepinephrine Norepinephrine 5 R 3 nitrobiphenyline is an a2C selective agonist as well as being a weak antagonist at the a2A and a2B subtypes 6 7 amitraz 8 Detomidine citation needed Lofexidine an a2A adrenergic receptor agonist 9 Medetomidine an a2 adrenergic agonist 10 Nonspecific agonist Edit Nonspecific agonists act as agonists at both alpha 1 and alpha 2 receptors Xylometazoline 11 Oxymetazoline 12 Apraclonidine citation needed Cirazoline 13 14 Epinephrine 15 Undetermined unsorted Edit The following agents are also listed as agonists by MeSH 16 ergotamine etilefrine indanidine mephentermine metaraminol methoxamine mivazerol naphazoline norfenefrine octopamine phenylpropanolamine propylhexedrine rilmenidine romifidine synephrine talipexoleClinical significance EditAlpha adrenergic agonists more specifically the auto receptors of alpha 2 neurons are used in the treatment of glaucoma by decreasing the production of aqueous fluid by the ciliary bodies of the eye and also by increasing uveoscleral outflow Medications such as clonidine and dexmedetomidine target pre synaptic auto receptors therefore leading to an overall decrease in norepinephrine which clinically can cause effects such as sedation analgesia lowering of blood pressure and bradycardia There is also low quality evidence that they can reduce shivering post operatively 17 The reduction of the stress response caused by alpha 2 agonists were theorised to be beneficial peri operatively by reducing cardiac complications however this has shown not to be clinically effective as there was no reduction in cardiac events or mortality but there was an increased incidence of hypotension and bradycardia 18 See also EditAlpha blocker Adrenergic agonist Beta adrenergic agonistReferences Edit Declerck I Himpens B Droogmans G Casteels R September 1990 The alpha 1 agonist phenylephrine inhibits voltage gated Ca2 channels in vascular smooth muscle cells of rabbit ear artery Pflugers Arch 417 1 117 9 doi 10 1007 BF00370780 PMID 1963492 S2CID 8074029 MacLean MR Thomson M Hiley CR June 1989 Pressor effects of the alpha 2 adrenoceptor agonist B HT 933 in anaesthetized and haemorrhagic rats comparison with the haemodynamic effects of amidephrine Br J Pharmacol 97 2 419 32 doi 10 1111 j 1476 5381 1989 tb11969 x PMC 1854522 PMID 2569342 Sagvolden T 2006 The alpha 2A adrenoceptor agonist guanfacine improves sustained attention and reduces overactivity and impulsiveness in an animal model of Attention Deficit Hyperactivity Disorder ADHD Behav Brain Funct 2 41 doi 10 1186 1744 9081 2 41 PMC 1764416 PMID 17173664 Atalik KE Sahin AS Dogan N April 2000 Interactions between phenylephrine clonidine and xylazine in rat and rabbit aortas Methods Find Exp Clin Pharmacol 22 3 145 7 PMID 10893695 Lemke KA 2004 Perioperative use of selective alpha 2 agonists and antagonists in small animals Can Vet J 45 6 475 80 PMC 548630 PMID 15283516 Crassous PA Cardinaletti C Carrieri A Bruni B Di Vaira M Gentili F Ghelfi F Giannella M Paris H Piergentili A Quaglia W Schaak S Vesprini C Pigini M August 2007 Alpha2 adrenoreceptors profile modulation 3 1 R m nitrobiphenyline a new efficient and alpha2C subtype selective agonist Journal of Medicinal Chemistry 50 16 3964 8 doi 10 1021 jm061487a PMID 17630725 Del Bello Fabio Mattioli Laura Ghelfi Francesca Giannella Mario Piergentili Alessandro Quaglia Wilma Cardinaletti Claudia Perfumi Marina Thomas Russell J Zanelli Ugo Marchioro Carla Dal Cin Michele Pigini Maria 11 November 2010 Fruitful Adrenergic a2C Agonism a2A Antagonism Combination to Prevent and Contrast Morphine Tolerance and Dependence Journal of Medicinal Chemistry 53 21 7825 7835 doi 10 1021 jm100977d PMID 20925410 Hsu W H and Lu Z X 1984 Amitraz induced delay of gastrointestinal transit in mice Mediated by a2 adrenergic receptors Drug Development Research Volume 4 6 655 680 Press Announcements FDA approves the first non opioid treatment for management of opioid withdrawal symptoms in adults www fda gov Retrieved 18 May 2018 Sinclair MD November 2003 A review of the physiological effects of alpha2 agonists related to the clinical use of medetomidine in small animal practice Can Vet J 44 11 885 97 PMC 385445 PMID 14664351 Haenisch B Walstab J Herberhold S Bootz F Tschaikin M Ramseger R Bonisch H 2009 Alpha adrenoceptor Agonistic Activity of Oxymetazoline and Xylometazoline Fundamental amp Clinical Pharmacology 24 6 729 39 doi 10 1111 j 1472 8206 2009 00805 x PMID 20030735 S2CID 25064699 Westfall Thomas C Westfall David P Chapter 6 Neurotransmission The Autonomic and Somatic Motor Nervous Systems Chapter Brunton LL Lazo JS Parker KL Goodman amp Gilman s The Pharmacological Basis of Therapeutics 11e AccessMedicine Anatomy and General Functions of the Autonomic and Somatic Motor Nervous Systems Archived from the original on 2011 09 30 Retrieved 2015 01 24 Horie K Obika K Foglar R 1995 Selectivity of the imidazoline a adrenoceptor agonists oxymetazoline and cirazoline for human cloned a1 adrenoceptor subtypes British Journal of Pharmacology 116 1 1611 8 doi 10 1111 j 1476 5381 1995 tb16381 x PMC 1908909 PMID 8564227 Ruffolo R R Jr Waddell J E 1982 Receptor interactions of imidazolines IX Cirazoline is an a1 adrenergic agonist and an a2 adrenergic antagonist Journal of Pharmacology and Experimental Therapeutics 222 1 29 36 PMID 6123592 Shen Howard 2008 Illustrated Pharmacology Memory Cards PharMnemonics Minireview p 4 ISBN 978 1 59541 101 3 MeSH list of agents 82000316 Lewis Sharon R Nicholson Amanda Smith Andrew F Alderson Phil 2015 08 10 Alpha 2 adrenergic agonists for the prevention of shivering following general anaesthesia Cochrane Database of Systematic Reviews 2015 8 CD011107 doi 10 1002 14651858 cd011107 pub2 ISSN 1465 1858 PMC 9221859 PMID 26256531 Duncan Dallas Sankar Ashwin Beattie W Scott Wijeysundera Duminda N 2018 03 06 Alpha 2 adrenergic agonists for the prevention of cardiac complications among adults undergoing surgery Cochrane Database of Systematic Reviews 2018 3 CD004126 doi 10 1002 14651858 cd004126 pub3 ISSN 1465 1858 PMC 6494272 PMID 29509957 External links Edit Media related to Alpha adrenergic agonists at Wikimedia Commons Adrenergic alpha Agonists at the US National Library of Medicine Medical Subject Headings MeSH Retrieved from https en wikipedia org w index php title Alpha adrenergic agonist amp oldid 1130391816, wikipedia, wiki, book, books, library,

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