The dried seeds of Physostigma venenosum, an African plant. They contain two alkaloids: cala-barine, the less important one; and physostigmine, or eserine, the active principle.

Physiological Actions

Applied to the eye, physostigmine is absorbed by the conjunctiva, and causes contraction of the pupil, with slight twitching of the eyelids, dimness of vision, and pain over the eyes.

Calabar bean acts as a depressant on the medulla and spinal cord, but does not affect the cerebrum, the mind remaining clear in cases of poisoning. In moderate doses it sometimes produces nausea, colic, and increased peristaltic motion, resulting in diarrhoea.

The heart is first stimulated, and then weakened, and the same contraction of the pupil takes place after its internal use.

Symptoms Of Poisoning

The first symptoms of poisoning are: giddiness, weak pulse, muscular feebleness, vomiting, and free purging. The respirations become slow and irregular, and death results from paralysis of the respiratory centre.

The poison is treated by emptying the stomach, applying external heat, and using artificial respiration.

Atropine is a physiological antagonist, and is given in doses not larger than gr. 1/10.

Recovery has taken place, by means of prompt emesis, after a dose of gr. xii.

Preparations.

Extractum Physostigmatis. Extract Of Physostigma

Average dose, gr. 1/8-0.008 Gm.

Tinctura Physostigmatis. Tincture Of Physostigma

Average dose,  xv.-I mil.

Physostigminae Salicylas. Physostigmine Salicylate

Average dose, gr. 1/60-0.001 Gm.