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(organic chemistry)
C15H21O2N3 An alkaloid; poisonous, colorless-to-pinkish crystals; soluble in alcohol and dilute acids; melts at 86°C; used as a source of salicylate and sulfate forms. Also known as calabarine; eserine.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



(also eserine), C15H21O2N3, the chief alkaloid of Calabar beans, which are the seeds of the tropical African woody vine Physostigma venenosum. Physostigmine was discovered in 1864 by the German chemists Jobst and Hesse; the first synthesis of the alkaloid was carried out in 1935 by the American chemists P. Julian and J. Pikl. A weak base, the alkaloid yields salts that readily crystallize. It is soluble in alcohol, ether, and chloroform. The structural formula is

Physostigmine is highly poisonous. It is used in medicine, where it is classified as a reversible anticholinesterase. When administered medically, physostigmine blocks the enzyme cholinesterase, thereby protecting acetylcholine from a rapid hydrolytic breakdown. Physostigmine thus induces effects in the organism that are outwardly similar to those induced by acetylcholine and cholinomimetic agents (contraction of the pupils, slowed heartbeat, intensification of uterine contractions and of peristalsis in the stomach and intestine).

The protection of acetylcholine effected by physostigmine has made possible the discovery that acetylcholine is given off at the endings of the parasympathetic nerves and that nerve impulses are transmitted chemically. Physostigmine salicylate is used medically as an anticholinesterase. It is used mainly in ophthalmology, where in drop form it serves to contract the pupils and to reduce the intraocular pressure arising from glaucoma; in ointment form, it is effective against keratitis. Hypodermic injections of physostigmine are sometimes prescribed for neuromuscular diseases (myasthenia), enteroparesis, and paresis of the urinary bladder. Physostigmine is an antidote for atropine and curarine. Synthetic substitutes for physostigmine, for example, neostigmine, are available.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Proudfoot, "The early toxicology of physostigmine: A tale of beans, great men and egos," Toxicological Reviews, vol.
Treatment of priapism with ketamine and physostigmine. Anaesth Analg 1982;61(8):705-7.
Physostigmine was used as positive control at the following concentrations: 2, 3, 4, 15, 30, and 40 [micro]g/0.195 mL.
(7.) Salen, P, Shih R, Sierzenski P, Reed J Effect of Physostigmine and Gastric Lavage in a Datura Stramonium-induced anticholinergic poisoning epidemic.
They also used curare to paralyse the animals and physostigmine to reverse the curarisation (3).
[11.] Eadie, GS, "The inhibition of cholinesterase by physostigmine and prostigmine", Journal of Biological Chemistry 1942; 146: 85-93.
In this regard, the effect of various cholinergic drugs has been evaluated in zebrafish and it has been reported that scopolamine (a cholinergic muscarinic receptor antagonist) impairs both the acquisition of the passive avoidance response and the retention of the learned response and that physostigmine (an acetylcholinesterase inhibitor that blocks the breakdown of the ACh released at the synaptic site) rescues the amnesic effects of scopolamine.
Asystole complicating physostigmine treatment of tricyclic antidepressant overdose.
Because of the risk of provoking convulsions, flumazenil is not recommended for reversal of benzodiazepine toxicity, and physostigmine does not have a recommended role in reversing GHB toxicity.
With the exception of animal-derived, digoxin-specific Fab antibodies to inactivate ingested plant-derived cardiac glycosides and physostigmine to reverse plant toxin-induced central anticholinergic syndromes, there are few remaining effective antidotes for most plant toxins.
Altered mental status from olanzapine overdose treated with physostigmine. Clin Toxicol (Phila).