Physostigma, or Calabar Bean, consists of the dried ripe seeds of Physostigma venenosum (Fam. Leguminosece), a climbing woody plant of Western Africa. Its principal activity is due to the alkaloid physostigmine, the salicylate salt of which is official. This should be kept from the light.

Properties of P. Salicylate (Eserine Salicylate):

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Do not taste.

Solubility: H20, 1 in 75; C2H5OH, 1 in 16.

To aq. sol. eserine add FeCl3 T. S.........................................................................................................................................................

Physostigmine is used by clinicians to stimulate unstriped muscle fibres in the intestines in cases of acute obstipation. Dose, 0.001 Gm. It is also used by ophthalmologists to reduce intra-ocular tension.