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Alpha-adrenergic agonist: Wikis


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An adrenergic alpha-agonist (or alpha-adrenergic agonist) is a drug that selectively stimulates alpha adrenergic receptors. The alpha-adrenergic receptor has two subclasses α1 and α2.



Although complete selectivity between receptor agonism is rarely achieved, some agents have partial selectivity.


α1 agonists

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

α2 agonists

α2 agonists: inhibits adenylyl cyclase activity. (reduce brainstem vasomotor center-mediated SNS activation; used as antihypertensives, sedatives & treatment of opiate and alcohol withdrawal symptoms). Selected examples are:


The following agents are also listed as agonists by MeSH.[4]

Clinical significance

Alpha-adrenergic agonists are used in the treatment of glaucoma by decreasing the production of aqueous fluid by the ciliary bodies of the eye.


  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". Pflugers Arch. 417 (1): 117–9. doi:10.1007/BF00370780. PMID 1963492.  
  2. ^ 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. PMID 17173664. PMC 1764416.  
  3. ^ 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.  
  4. ^ MeSH list of agents 82000316

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