Calabar Bean

CALABAR BEAN (Faba calabarica s. Semen Physostigmatis), the seed of a perennial wild plant, Physostigma venenosum (family Papilionaceae), growing on the western coast of Africa, at the mouths of the Niger and Calabar rivers. It contains an amorphous, tasteless and odorless alkaloid, physostigmin (synonym eserine), with the formula C15H21N3O2, and in addition, eseridine, which is similar to physostigmin but acts more weakly, and calabarine, which is little studied and causes convulsions. Only physostigmin is used therapeutically, in the form of the most soluble crystalline salts of salicylic or sulfuric acid. Solutions easily decompose, turning reddish (from the transformation product rubreserine), and lose their strength in the process. Physostigmin stimulates the endings of the parasympathetic nervous system, and as a result of poisoning, there is a strong contraction of all organs with smooth muscle (gastrointestinal tract - vomiting, diarrhea; iris - miosis), increased secretion of glands (digestive tract, bronchial, etc.), stimulation of the inhibitory apparatus of the heart - bradycardia, etc. In addition, there is excitation of the central nervous system (convulsions) and fibrillar contractions of skeletal muscles, which continue for some time after death. The antidote is atropine. It is used as

Physostigma venenosum Balfour. myoticum in a ¹/₅-Va% solution (eye drops), and in veterinary practice also for atonic constipation. Dose per administration: Physostigmini salicylici 0,001 (Ph. VII).