(Woorari.)

Origin. - An extract of uncertain composition prepared by the natives of South America as an arrow-poison. Dr. Jobert reported to the French Academy in 1878 that the poison was prepared chiefly from Strychnos Castelnceana and other species of Strychnos, and Cocculus toxiferus, containing also variable quantities of other poisonous plants, such as Didelphys cancrivora, etc. It is altogether probable that its ingredients include the poison of venomous reptiles. Each tribe, however, has its own method for preparing curare, and the precise formulas are clan secrets. Bohm's studies in 1887 were among the first to give accurate details of the varieties, but these change from time to time.

Description and Properties. - The extract is a blackish-brown, friable solid, brittle or hygroscopic, of a very bitter taste; almost completely soluble in dilute alcohol. Cold water dissolves about 75 per cent., which portion contains the poisonous alkaloids and is insoluble in ether and but sparingly soluble in absolute alcohol.

The active constituents vary somewhat. Curarine is the name given by Bohm to the alkaloid, or impure nitrogenous base, which produces the typical paralyzing effects of curare. Other alkaloids have been named curin and protocurarine, the former inert, the latter supposed to be very active. Bohm's studies have not been subjected to careful revision.

Dose. - 1/20 - 1/2 grain (0.003-0.03 Gm.), hypodermically given.

Dose Of Curarine. - 1/200-1/100 grain (0.0003-0.0006 Gm.), hypodermically.

Antagonists and Incompatibles. - The excito-motors are antagonistic. Tannic acid and the caustic alkalies are chemically incompatible.

Synergists. - The depresso-motors.

Physiological Action. - When applied to the denuded skin it is an irritant.

Circulatory System. - Medicinal doses render the pulse fuller and rapid from vagus depression; there is marked dilatation of the blood-vessels of the skin and the various glands; while the blood-pressure, though little affected by small doses, is decidedly lowered by large ones. The ganglionic paresis causes the fall in pressure.

Nervous System. - No cerebral action is caused by moderate doses. The action on the medulla is slight in moderate dosage.

Spinal Cord and Peripheral Nerves. - The typical action of curare is on the end-plates of the motor nerves of striated muscles. These are paralyzed, the smaller muscles being first involved, hence ptosis, etc. The respiratory muscles are first acted on. Unstriped muscle terminations are not affected. Sensory nerves are unaffected. The peripheral ganglia of the sympathetic are paralyzed. The dilated pupil, the increased peristalsis, and involuntary evacuations are indications of this sympathetic nerve depression.

Respiratory System. - Curare is a powerful respiratory depressant, paralyzing the ends of the motor nerves distributed to the respiratory muscles. When lethal doses have been given, the paralysis may become central. Death results from asphyxia.

Curare is absorbed very slowly from the stomach and is probably little acted on in the body, as in animals most of it has been recovered from the urine.

Absorption and Elimination. - When ingested the process of absorption is exceedingly slow, but when injected into the circulation the drug is rapidly absorbed.

It is quickly eliminated by the kidneys, causing sugar to appear in the urine. A portion of the poison is also excreted with the feces. The sweat, saliva, nasal mucus, and tears, although their secretion is greatly increased by the drug, do not seem to share in the process of elimination. Metabolism in general is checked.

Poisoning. - Curare is a rapid and active poison. The movements of the heart are greatly accelerated; the pulse is weak and dicrotic; the temperature is elevated, and the respiration correspondingly depressed; extreme muscular weakness ensues, with incoordination of movements; the urine becomes saccharine. Finally, paralysis of the extremities and the respiratory muscles supervenes, death occurring from respiratory paralysis.

Treatment of Poisoning. - The same as in the treatment of poisoning from conium, with catheterization of the bladder to favor elimination, and artificial respiration.

Therapeutics. - While of great scientific interest and of value for experimental purposes in ascertaining the effect of certain drugs upon animals, the therapeutic uses of curare are very limited. It is indicated only in those diseases for which conium has proved of some service.

Contraindications. - The same as for conium.

Administration. - The crude drug or the alkaloid curare should be given hypodermically.