Definition. - The neutral hydrochloride of the alkaloid cocaine.

Description and. Properties. - Colorless, transparent crystals or a white, crystalline powder, odorless, of a saline, slightly bitter taste, and producing upon the tongue a tingling sensation followed by numbness of some minutes' duration. Permanent in air, soluble in 0.4 part of water and 2.6 parts of alcohol at 250 C.; very soluble in boiling water and in boiling alcohol.

Dose. - 1/8-2 grains (0.008-0.12 Gm.) [1/2 grain (0.03 Gm.), U. S. P.].

Antagonists and Incompatibles. - Morphine, chloral, amyl-nitrite, alcohol, chloroform, and ether are physiological antagonists. The most direct opponents are chloral and morphine.

Cocaine is incompatible with caustic alkalies and the alkaline carbonates and bicarbonates, as well as with bichloride of mercury, iodine and the iodides, ammonia, zinc chloride, and borax.

Synergists. - Medicinally, its cerebral effects may be enhanced by the cerebral stimulants, such as alcohol, cannabis Indica, and belladonna, while its analgesic and anesthetic action may be aided by carbolic acid, atropine, opium, and conium. When used as a mydriatic, atropine serves as a valuable synergist.

Physiological Action. - For our first knowledge of the physiological properties of coca we are indebted to its empirical use among the natives of Peru. The history of the drug is replete with interest and romance. It was regarded as the living representation of the Deity, the ground whereon it grew being held sacred. During the reign of the Incas its use was a royal privilege, the people being compelled to obtain permission from the governor to avail themselves of its benefits. Later it was adopted indiscriminately.

The native coqueros (coca-chewers) have learned from experience that they can climb the Andes, work laboriously in the mines, and endure fatigue and hunger more hardily when chewing the leaves of the plant, and from time immemorial the drug has been recognized by observers as possessing powerful nutritive, stimulant, and restorative properties.

In describing the action of the crude drug the author can add little to the words of Linnaeus, who long ago wrote that coca possessed "the penetrating aroma of vegetable stimulants, the astricting and fortifying virtues of an astringent, the antispasmodic qualities of bitters, and the mucilaginous nutritive properties of analeptics or of alimentary plants." "This leaf," he adds, "exhibits with energy its action on all parts of the animal economy." Since the isolation of the alkaloid cocaine, to which the drug owes its physiological and medical properties, by Gaedeke in 1855, and the subsequent study of it by eminent pharmacologists and therapeutists, we have learned more of the physiological action of coca. Its effect upon different systems are here described in detail.

Externally and Locally. - Cocaine is anagelsic, anesthetic, and ischemic. Upon the unbroken skin it has no action, but upon mucous membranes or the subcutaneous tissue it produces complete local analgesia. The surface to which it is applied becomes paler than normal, owing to contraction of the blood-vessels, but afterward reddens and appears turgescent through secondary dilatation of the vessels. The absorption of the drug by mucous membranes varies with the locality to which it is applied - with difficulty from the conjunctiva, yet with great readiness from the Schneiderian membrane, producing its characterisic constitutional effect.

Applied to the conjunctiva, or even taken internally, cocaine causes a transitory contraction of the pupil, soon followed by dilatation. The accommodation is impaired, but not completely destroyed. The ocular tension is lowered. The light reflex is not abolished. There may be a slight exophthalmos.

The analgesic action of cocaine applied locally is due to the depression of the ends of the nerves of pain-sensation. It does not affect the ordinary sensations of touch or temperature to anything like the extent that it affects pain-sensation. It dilates the pupil by stimulating the ends of the sympathetic nerve, which innervates the radiating fibers of the iris.

In addition to its local analgesic action the drug possesses the power of destroying the functions of the nerves of special sense, so taste and smell are abolished. When applied locally or taken internally it primarily checks many of the secretions, though those from the pancreas and liver seem to be uninfluenced by its internal use. The secondary impression of cocaine, however, when the blood-vessels become dilated, is accompanied by increased secretions.

Internally - Digestive System. - Although it has been shown by experiments upon animals that cocaine is incapable of sustaining life, it diminishes in man the sensation of hunger, owing to its local anesthetic action upon the mucous membrane of the stomach, so that the coqueros and the modern habitues are able to abstain from food for days, thirst also being allayed. This diminution of hunger does not seem to impair appetite and digestion until habitual cocaine mania destroys the gastric functions almost entirely. This contributes to the great emaciation of these patients.

On account of its stimulant action upon the constrictor fibers of the great sympathetic nerve, under the influence of moderate doses peristalsis is largely increased in the stomach and intestines, very large or poisonous doses, on the contrary, causing great sluggishness of the bowels.

Circulatory System. - Medicinal doses of cocaine increase the force and frequency of the cardiac contractions, and also arterial pressure. Large or poisonous doses render the pulse slow, soft, and weak and lower arterial tension. The exact modus operandi is not fully determined, but there is direct stimulation of the heart or its accelerator mechanism. There is a marked rise in blood-pressure due to the cardiac stimulation and to a marked contraction of the blood-vessels from vasoconstrictor stimulation.