This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
Coca. - Synonyms. - Erythroxylon. Cuca. The leaves of Erythroxy-lon Coca, Lamarck (nat. ord. Lineal).
Peru and Bolivia; cultivated.
Varying between ovate, lanceolate, and obovate-oblong, and from 2 to 5 or 7 cm. in length; short-petiolate, entire, rather obtuse or emarginate at the apex, slightly reticulate on both sides, with a prominent midrib, and on each side of it a curved line running from base to apex; odor slight and tea-like; taste somewhat aromatic and bitter. When chewed, it temporarily benumbs the lips and tongue.
It contains at least three alkaloids, viz., (1) Cocaine, which is methyl benzoyl ecgonine, 0.2 per cent.; (2) Cocamine or isatrophyl cocaine; (3) Cinnamylcocaine. Also (4) Coca-tannic acid and (5) Coca-wax. Different specimens vary very much in strength of Cocaine. Fresh specimens are stronger than those that have been kept.
C17H2I No4hc1 =338.71. The hydrochlorate of an Alkaloid obtained from Coca.
Agitate with Ether an aqueous solution of an acidulated Alcoholic extract, make alkaline with Sodium Carbonate; separate and evaporate the Ethereal liquid; purify by repetition; decolorize, neutralize with Hydrochloric Acid, and re-crystallize.
Colorless, transparent crystals, or a white, crystalline powder, without odor; of a saline, slightly bitter taste, and producing upon the tongue a tingling sensation followed by numbness of some minutes' duration. Permanent in the air.
In 0.48 part of water, and in 3.5 parts of Alcohol; also soluble in 2800 parts of Ether, or in 17 parts of Chloroform.
Dose, 1/8 to 2 gr.; .008 to .12 gm.
Cocaine has little action on the unbroken skin, but if injected subcutaneously or applied to mucous membranes - as, for example, those of the eye, nose, mouth, rectum, vagina - it produces complete local anaesthesia to pain, touch, heat and cold, so that small operations can be performed without the patient feeling them. A 5 to 10 per cent. solution of the hydrochlorate is strong enough thus to paralyze the sensory nerves. Much larger doses must be applied to motor nerves to paralyze them.
Gastro-intestinal tract. - Applied to the nose and tongue cocaine abolishes smell and taste respectively, and when it is taken internally, the gastric mucous membrane experiences its anaesthetic influence. Therefore the sensation of hunger is deadened, and persons taking cocaine can go a long time without feeling the want of food; but the drug is not a food, for the body rapidly wastes. Because of its local anaesthetic effect it sometimes stops vomiting. Very large doses may lead to diarrhoea.
Circulation. - Large doses depress the vagus, and therefore the pulse quickens, and as the vaso-motor centre is stimulated the blood-pressure rises; larger doses slow the pulse from stimulation of the vagus. Cocaine constricts the arterioles.
Respiration. - It acts upon the respiratory centre, first stimulating it, so that the rapidity and depth of respiration are increased; but soon depression of the centre follows, the respiratory movements become feeble, and death takes place from asphyxia.
Nervous system. - Cerebrum. - Moderate doses greatly increase the bodily and mental power, and give a sense of calm and happiness, with abolition of bodily and mental fatigue. This greater physical energy renders possible the performance of long, exhausting muscular feats. For this, and for the extreme sense of peace produced, coca leaves mixed with clay or ashes are chewed by thousands of the inhabitants of Peru and the neighboring countries. It is said that forty million pounds of the leaves are annually harvested. A single large dose causes mental excitement, delirium and ataxia, with subsequent headache and depression. This ataxia is due to impairment of conduction of sensory impressions from the effect of the cocaine on peripheral sensory nerves. An excessive indulgence in the habit of coca-chewing leads to indigestion, extreme emaciation, insomnia and enfeeblement of intellect. In animals coca causes cerebral convulsions.
Eye. - When a solution of cocaine of about 4 per cent. is dropped into the eye local anaesthesia is produced, first of the conjunctiva and cornea, later of the iris. It is attained in about seven minutes, and lasts about the same time. At first there may be a transitory contraction of the pupil. This is probably due to reflex action, and soon gives way to wide dilatation.
The maximum is attained in an hour or two. The normal state is regained in from twelve to twenty-four hours. The dilated pupil is freely responsive to light, and the dilatation is rapidly overcome by physostigmine. The ocular tension is slightly lowered, and the palpebral aperture is widened. Accommodation is partially, but never completely, paralyzed. These effects are chiefly due to irritation of the sympathetic, and as they are quickly produced by dropping the drug in the eye they are probably local. All these effects are slowly produced if large doses of cocaine are taken internally. Strong solutions or weak solutions frequently applied desiccate the corneal epithelium.
Muscles. - The amount of muscular work of which the body is capable is increased by cocaine, how, is not known. The excretion of urea and nitrogenous metabolism are unaltered.
Temperature. - This may rise in cocaine poisoning.
Kidneys. - Cocaine is most likely excreted by these organs. It diminishes sexual excitability.