TY - CHAP M1 - Book, Section TI - Antidotes in Depth A1 - Howland, Mary Ann A2 - Hoffman, Robert S. A2 - Howland, Mary Ann A2 - Lewin, Neal A. A2 - Nelson, Lewis S. A2 - Goldfrank, Lewis R. Y1 - 2015 N1 - T2 - Goldfrank's Toxicologic Emergencies, 10e AB - Physostigmine is a carbamate that reversibly inhibits cholinesterases in the peripheral nervous system and central nervous system (CNS).46 The tertiary amine structure of physostigmine permits CNS penetration and differentiates it from neostigmine and pyridostigmine, which are quaternary amines that have limited ability to enter the CNS. The inhibition of cholinesterases prevents the metabolism of acetylcholine, allowing acetylcholine to accumulate and antagonize the antimuscarinic effects of xenobiotics such as atropine, scopolamine, and diphenhydramine.54 Although physostigmine previously was used as an antagonist to the antimuscarinic effects of cyclic antidepressants and phenothiazines, this use is no longer recommended because of a poor risk-to-benefit ratio, given the potential for exacerbation of life-threatening cardiotoxicity. Similarly, physostigmine has a poor risk-to-benefit ratio in the management of presumed γ-hydroxybutyric acid (GHB) toxicity.4,48,55 Atypical antipsychotics have complex pharmacologic effects. Although some atypical antipsychotics, such as olanzapine, have significant antimuscarinic side effects, the benefit of treating these anticholinergic effects with physostigmine must be weighed by the potential risks of exacerbating cardiotoxicity.19,47,53 SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/29 UR - accesspharmacy.mhmedical.com/content.aspx?aid=1108421741 ER -