CURARA. — This substance—known 1 also as curare, woorari, ourari, urari, woorara, wourali, and ourali, though it has been before the medical profession for more than half a century—is prac tically unknown as to its source and composition. There is considerable evi dence to show that it is derived in part from two or more trees of the strych nine group, from the Menispermum coc culus (Cocculus Indicus), and various un known plants. It comes chiefly from the valley of the Orinoco,—Brazil, British and French Guiana, Venezuela, and Co lombia,—where it serves certain savage tribes as an arrow-poison. It is by no means a stable or uniform substance; some appear to have mingled with it the poisonous principle of Jatropha (Mani hot utilissima), known as obi or obiah poison in the -West Indies, while that from Colombia is of lighter color, appear ing as a yellowish-brown, amorphous, deliquescent powder. Brazilian and Guianian curare is a blackish, intensely bitter, hygroscopic mass of resinous ap pearance. Both are soluble in dilute alcohol to the amount of 70 per cent. and in the water to 75 or 85 per cent., but insoluble in ether. Two alkaloids have been segregated known as "cura rine" and "curine." The Indians of the Orinoco prepare two kinds of curara: one a relatively mild poison used in the chase, its chief source being Strychnos gubleri; the other much stronger, a war poison, from the S. to.rifera. Planclion (Provincial Med. Jour., July, 'SS).
Preparations and Doses.—Curara, V30 to V, grain.
Curarine, 1/2. to lho grain. Curarine sulphate, 1/200 to 1/,00 grain. Curine, uncertain.
Physiological Action.—Neither curara nor its alkaloids are ever employed ex cept enderroically (rarely) or hypoder mically, since it is held that all are de composed in the stomach and rendered practically inert. The latter is not true, however; but the process of absorption is extremely slow; but when employed subcutaneously it is rapidly absorbed. Elimination is rapid, chiefly by the kid neys, causing sugar to appear in the urine, and partly with the fmces; per spiration, saliva, nasal mucus, and tears, though greatly increased, do not seem to share in the eliminative process.
it is not absorbed by intact integu ments, but is absorbed (though with dif ficulty) by mucous membrane. "When introduced into the system and brought in contact with the systemic tissues, the I drug develops identical biological effects in dogs, cats, rabbits, pigeons, amphib ians, batrachians, reptiles, fishes, crus taceans, insects, a.nd ammbm. According t to the duration of its contact with various organs and tissues, curara may paralyze either the central nervous sys tem or terminations of motor nerves of any muscular structure (including the heart) and of the vagi; this least rap idly in dogs and rabbits. In mammals
generally it causes death by paralyzing the respiratory centres, but not the pe ripheral respiratory nerves. The proxi mate cause of the biological effects of curara is, probably, constituted by the drug inducing some alterations in the protoplasm of both nervous and muscular structures, though to a different extent, and not simultaneously. Dogiel and Nikolski (Medit. Oboz., No. 3, '90; Med. Chron., June, '90).
Curarine paralyzes the motor nerve endings, but has no effect on sensory nerves. The irregularity and the early depression of the reflexes are not due to an action on the spinal cord or the sensory nerves, but to an inhibitory in fluence exercised upon the cord by a stimulation of the higher centres. The alkaloid likewise exerts a tetanic action on the cord, but the reason why it does not induce tetanic spasm, in the great majority of cases, when given hypo dermically is because the circulatory changes produced are such as to prevent the drug from having access to the cord, and because these changes of themselves produce spinal paralysis. With larger doses there is dilatation of the abdominal vessels, and hence accumulation of blood, little or nothing of this fluid entering the empty ventricle, notwithstanding that the heart may continue to beat. Curarine causes an almost immediate fall of blood-pressure in mammals; it occurs even after section of vagi, after a paralyzing dose of atropine, after division of all the cardiac nerves, after section of the spinal cord, and after paralysis of the central reflexes by urethane. The cause, therefore, of the fall of pressure must be due to a direct action upon the peripheral nerves or upon the muscles of the blood-vessel walls. It was found, however, that when an injection of barium was made into the circulation a rise of pressure was produced, while, on the other band, no such action was effected by stimulation of the peripheral nerves. Again, the vasomotor centre was found to be active by the appearance of the "Traube Hering" curves during the cessation of respiration by the action of the drug. This evidently proves that curarine causes a fall of pressure solely by a paralyzing influence exercised on the vasomotor nerves. The inhibition of the vagi is destroyed by curarine easily in cats, less so in dogs, and with difficulty in rabbits. Small doses in a healthy rabbit caused the appearance of albu min, blood-pigment. and blood in urine.