Chemistry:Alpha-2 blocker
Alpha-2 blockers (or α2 blockers) are a subset of the alpha blocker class of drugs and are antagonists to the α2 adrenergic receptor. They are mainly used in research, having found limited clinical application in human medicine. They are extensively used in veterinary medicine to reverse the effects of alpha-2 agonist drugs used as sedatives, like xylazine, medetomidine and dexmedetomidine. Alpha-2 blockers increase noradrenaline release.
Uses
Yohimbine, historically used as an aphrodisiac, is sometimes used in veterinary medicine (although now largely replaced by atipamezole) for reversing the effects of α2s such as medetomidine that are used as sedatives during surgery.[1]
Mechanistically, α2 blockers increase adrenergic, dopaminergic and serotonergic neurotransmitters and induce insulin secretion, decreasing blood sugar levels.[2]
Withdrawal from α2 blockers can be difficult or dangerous as the global downregulation of neurotransmitters may cause symptoms of depression and other neurological problems, and increased blood sugar levels together with decreased insulin sensitivity can cause diabetes. Moreover, reduced microcirculation together with adrenaline supersensitivity in organs such as liver can occur.{{citation needed|date=June 2020}
Examples
Examples include atipamezole,[3] efaroxan, fipamezole, idazoxan,[4] yohimbine, and rauwolscine, phentolamine.
References
- ↑ Lemke, KA (June 2004). "Perioperative use of selective alpha-2 agonists and antagonists in small animals.". The Canadian Veterinary Journal 45 (6): 475–80. PMID 15283516.
- ↑ Fagerholm, Veronica; Haaparanta, Merja; Scheinin, Mika. "α2-Adrenoceptor Regulation of Blood Glucose Homeostasis". Basic & Clinical Pharmacology & Toxicology. doi:10.1111/j.1742-7843.2011.00699.x. PMID 21418144. https://onlinelibrary.wiley.com/doi/10.1111/j.1742-7843.2011.00699.x.
- ↑ "The alpha 2-adrenoceptor antagonist atipamezole potentiates anti-Parkinsonian effects and can reduce the adverse cardiovascular effects of dopaminergic drugs in rats". Naunyn-Schmiedeberg's Arch. Pharmacol. 368 (5): 342–51. November 2003. doi:10.1007/s00210-003-0827-z. PMID 14566451.
- ↑ "Effects of alpha-2 adrenoceptor agonists and antagonists on circling behavior in rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal pathway". J. Pharmacol. Exp. Ther. 288 (2): 798–804. February 1999. PMID 9918591. http://jpet.aspetjournals.org/cgi/pmidlookup?view=long&pmid=9918591.
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