Description of the drug: Physostigmine (Physostigminum)

PHYSISTIMMIN (Physostigminum).

Physostigmine, or eserin, is the main alkaloid of the so-called calabar beans - the seeds of the West African plant Physostigma venenosum, the family. Beans (Leguminosae).

According to its chemical structure, physostigmine refers to indole derivatives, contains a urethane group.

In medical practice, physostigmine salicylate (Physostigmini salicylas) is used.

Synonyms: Eserina salicylate, Eserini salicylas, Physostigmine salicylate, Physostigminum salicylicum.

Colorless shiny prismatic crystals. It is difficultly soluble in water (1: 100), soluble in alcohol (1: 12). From the action of light and air, the powder and solutions turn red and become inactive. Solutions are prepared exepte aseptically or subjected to tindalization.

Physiostigmine is one of the main representatives of anticholinesterase substances of reversible action. In large doses, in addition to the effect on cholinesterase, it can exert a direct effect on cholinergic receptors (as well as other anticholinesterase drugs).

Physiostigmine salicylate is used mainly in ophthalmic practice to narrow the pupil and lower the intraocular pressure in glaucoma. Enter into the conjunctival bag for 1 - 2 drops of 0.25 - 1% solution 1 - 6 times a day. The narrowing of the pupil usually occurs after 5 to 15 minutes and lasts 2 to 3 hours or more. In keratitis, ointments with physostigmine salicylate (0.2-0.25%) are used.

In glaucoma, physostigmine causes a greater decrease in intraocular pressure than pilocarpine, but it relatively often causes pain in the eye and the superciliary due to a strong reduction in the iris. For this reason physostigmine is more often used in acute glaucoma and in the case when pilocarpine is not effective enough. A good effect is provided by a combination of physostigmine (0.25%) with pilocarpine (1%).

Physostigmine is sometimes used also in the clinic of nervous diseases with neuromuscular diseases, as well as with paresis of the intestine (0.5-1 ml of 0.1% solution under the skin). More widely used for these purposes have galantamine, oxazil, proserin, and with paresis of the intestine and bladder - acekledin.

In recent years, try to use physostigmine (subcutaneously) to improve the condition of patients with Alzheimer's disease. It was found that in this disease the content of the cholinacetyltransferase in the cerebral cortex, an enzyme participating in the biosynthesis of acetylcholine, is reduced. The resulting disorder of cholinergic innervation is accompanied by clinical symptoms characteristic of the disease (memory impairment, etc.). It was found that physostigmine improves the condition of patients suffering from Alzheimer's disease. However, physostigmine does not provide a sufficiently stable therapeutic effect. At the same time undesirable side effects are observed, which limits the use of this drug.