(-)-Physostigmine is an alkaloid that has been found in Calabar beans and a cholinergic agent.^1,2It inhibits acetylcholinesterase (AChE; IC₅₀= 0.67 nM).²(-)-Physostigmine (10 µM) inhibits ChE and increases vagal stimulation-induced ACh output in isolated chicken heart.³In vivo, (-)-physostigmine (200 and 400 µg/kg) induces decentralized lower eyelid contractions and increases blood pressure in anesthetized rats.⁴

1.Proudfoot, A.The early toxicology of physostigmine: a tale of beans, great men and egosToxicol. Rev.25(2)99-138(2006) 2.Ogura, H., Kosasa, T., Kuriya, Y., et al.Comparison of inhibitory activities of donepezil and other cholinesterase inhibitors on acetylcholinesterase and butyrylcholinesterase in vitroMethods Find. Exp. Clin. Pharmacol.22(8)609-613(2000) 3.Dieterich, H.A., Kaffel, H., Kilbinger, H., et al.The effects of physostigmine on cholinesterase activity, storage and release of acetylcholine in the isolated chicken heartJ. Pharmacol. Exp. Ther.199(1)236-246(1976) 4.SzeberÉnyi, J., Varga, A., PongrÁcz, M.F., et al.Centrally mediated contraction of the lower eyelid elicited by anticholinesterases in anaesthetized ratsJ. Pharm. Pharmacol.24(1)85-86(1972)