Coca,—Coca, Cuca.

Source and Composition. The leaves of Erythroxylon Coca, a small Peruvian shrub of the nat. ord. Lineae, also called Cuca. It contains an active, crystalline alkaloid, named Cocaine, which by heat and HCl Acid is resolved into Benzoic Acid and another alkaloid, Ecgonine;—also a volatile, liquid alkaloid Hygrine, an aromatic oil and Coca-tannic Acid. Dose of the leaves, ʒss-ij.

Coca should not be confounded with Cocoa, a beverage prepared from the seeds of Theobroma Cacao, the Chocolate-tree, for which see page 131.

Preparations.

Extractum Cocae Fluidum, Fluid Extract of Coca,—Dose, ʒss-ij.

Cocainae Hydrochloras, Cocaine Hydrochlorate,—soluble in ½ of water and in 31/2 of alcohol. Dose, internally, gr. ⅛-j; by hypodermic injection, gr. ⅛-½.

*Cocainae Oleas, Oleate of Cocaine,—a 10 per cent. solution of the alkaloid in Oleic Acid, for external use.

*Wines, Glyceroles, Pastes, Lozenges, etc., of Coca,—are sold in great variety.

Physiological Action. In small doses Cocaine is a cerebral cardiac, respiratory and nervous stimulant, and a diuretic. It improves digestion, stimulates respiration, increases the heart's action, raises the arterial tension, and exalts the irritability of the sensory nerves. It stimulates the brain by increasing its blood-supply, producing wakefulness and marked diminution of the senses of fatigue and hunger. Though decidedly diuretic, it lessens the quantity of urea by checking the processes of waste, thus acting as an indirect nutrient, and enabling the body to maintain its energy on a lessened supply of food. It increases the cutaneous circulation, flushing the surface, exciting perspiration and a sense of beat, and does actually raise the body-temperature. It dilates the pupil, both when locally applied and when taken systemically,—and stimulates intestinal peristalsis as well as the evacuation of the bladder in a few minutes after its ingestion.

An overdose produces symptoms of cardiac and respiratory embarrassment in a very short time. The pulse, at first quick and forcible, becomes small, rapid and intermitting;—the heart apparently standing still in systole once in every 10 or 12 beats. Respiration is slow and shallow, and a sense of "tightness" about the chest is very marked;—the skin grows cold and clammy, and the subject is seized with a sense of impending dissolution. Death occurs in animals by paralysis of respiration,—but in man there seems to be a tetanoid spasm of the cardiac muscle, which is equally dangerous to life. Other symptoms are impairment of coordination, hallucinations arid delirium. Lethal Doses paralyze the intra-cardiac motor ganglia, the posterior columns of the cord and the sensory nerves, and the respiratory centre.

As a Local Anaesthetic the power of Cocaine is very great over a limited area. Applied to such structures as the Schneiderian membrane, mucous covering of the glans penis; or injected hypodermically in other locations, it blanches the structures and causes a profound but temporary anaesthesia throughout a small space. Applied to the tongue it temporarily destroys both taste and tactile sensibility ;—to the ocular conjunctiva, it produces profound anaesthesia of that membrane, together with dilatation of the pupil, partial paralysis of accommodation, enlargement of the palpebral fissure, slight lachrymation, and sometimes temporary ptosis. This profound degree of anaesthesia is thought by some to be caused by its paralyzing the terminal twigs of the sensory nerves,—by others to be due to vaso-motor action rendering the nerves bloodless and therefore unable to transmit sensory impressions. It produces mydriasis by stimulation of the ends of the sympathetic in the iris, and does not affect the third nerve or the sympathetic centre.

In general action, Cocaine resembles Atropine very closely, especially in its influence upon the pulse and blood-pressure, the respiration, pupils, salivary and sweat-glands and intestinal peristalsis. In its symptoms, both from large and small doses, it exactly parallels Sparteine, another cardio-inhibitory depressant.

Antagonists. Amyl Nitrite combats the earliest symptoms of cardiac depression,—then Alcohol and Opium as stimulants to the heart, also Artificial Respiration. The most direct antagonist is Chloral, so also are Chloroform and Ether. Morphine is also directly antagonistic at almost all points.

Therapeutics. Coca-leaves are habitually chewed by the Peruvian Indians, to sustain them during arduous labor. Their example was imitated by Weston, the pedestrian, during his protracted walks. In South America, it is used by 8 millions of people, much as we use tea and coffee. It is useful in—

Wasting Diseases, as a stimulant to digestion, and to retard waste.

Convalescence from fevers and other acute maladies,—a Wine of Coca.

Migraine and Neuralgia, with depression,—it is of real utility.

Vomiting of Pregnancy, and vomiting from any cause, it is efficient, even in the vomiting of Yellow Fever; 6-10-minim doses of a 4 per cent. solution every hour by the mouth.

Stomatitis, Gastralgia,—for its benumbing effect on the mucous membrane.

As a Local Anaesthetic,—Cocaine has numerous applications, which are being extended more widely every day. It is already a necessity to the ophthalmologist and the laryngologist, while for minor operations in general surgery and to relieve superficial pain, its use is becoming almost universal. In congestions of mucous surfaces it is being freely employed, also as a soothing and antiphlogistic application in skin diseases, to the uterus in labor, hypodermically for superficial neuralgiae, and locally for itching from any cause.

Rhus Poisoning, by either the oak or ivy,—is promptly controlled by the application of a 5 per cent. solution or oleate, freely over the affected surface. It gives instant relief from the burning and itching, and speedily reduces the dermatitis. (Observation by author.)

As a Mydriatic for ophthalmological use,—Cocaine has peculiar qualities which make it the most serviceable of the class. The dilatation produced by it is great, is quickly attained, lasts only 12 to 20 hours, is promptly overcome by the application of Eserine, and is not accompanied by much photopbobia. The latter is due to the fact that the cocainized pupil is not rigidly dilated, (as with Atropine), but reacts to light. The accommodation, moreover, is greatly reduced, but not entirely paralyzed, and is quickly regained.

A Compend of Materia Medica, Therapeutics, and Prescription Writing, 1902, by Sam'l O. L. Potter, M.D., M.R.C.P.L.