Coca. Cocae Folia. U. S. P. VIII. Br. 1898. Coca Leaves. Cuca, Feuilles de Coca, Fr. Cocablätter, G. Coca del Peru, Ipadu, Sp.—"The dried leaves of Erythroxylon Coca Lamarck (Fam. Erythroxylaceae), known commercially as Huanuco Coca, or of E. Truxillense Rusby, known commercially as Truxillo Coca, yielding when assayed by the process given below, not less than 0.5 per cent. of the ether-soluble alkaloids of Coca," U. S. VIII. "The dried leaves of Erythroxylum Coca, Lam., and its varieties." Br., 1898.
The coca plants are shrubs or small trees, some of the species reaching the height of fifteen or twenty feet. It is conjectured that the original habitat was in the Peruvian mountains, from 7° South to 10° North, but either spontaneously or through cultivation the coca shrubs have spread until they are found in the whole Eastern curve of the Andes, from the Straits of Magellan to the borders of the Caribbean Sea, growing on the moist sides of the mountains at the elevation of 1500 to 6000 feet, the climatic requisites being moisture and equable temperature, with a mean of about 17.7° C. (64° F.) The wild coca shrub commonly reaches the height of 12 feet, and some are 18 feet, but the cultivated coca is usually kept down to about 6 feet. The leaves are gathered three times a year; the first harvest, or preliminary picking, is taken at the time of the trimming of the bushes, from the cut-off twigs. Then about the end of June, a scanty crop is gathered, while the last' crop of the season is gathered in October or November. Harvesting must always take place in dry weather, so that the fresh leaves when spread out in layers two or three inches thick on the drying pavement can be collected in six or eight hours.
The coca plant, which is propagated from the seed in nurseries, begins to yield in eighteen months, and continues productive for half a century. The leaves, when mature, are carefully picked by hand so as to avoid breaking them or injuring the young buds, are slowly dried in the sun, and are then packed in bags (cestos) holding from twenty-five to one hundred and fifty pounds each. They were in general use among the natives of Peru at the time of the conquest, and have continued to be much employed to the present time. It is affirmed that nearly ten million dollars' worth, or forty million pounds, are annually produced, some plantations yielding three or four harvests a year. The importations into the United States have averaged for some years past about 1,000,000 pounds. For details as to method of cultivation, etc., see T.G., Jan., 1886; also C. D., 1897, 182'. Two varieties of the coca leaf occur in the commerce of the United States, namely, the so-called Huanuco coca, and the Truxillo coca, the Huanuco variety being produced in Bolivia, Huanuco, Brazil, Venezuela and Argentina, while the Truxillo coca is produced chiefly in Northern Peru. The great variation in the leaves and other portions of the coca plant, produced by its long-continued cultivation, has produced much doubt and discussion as to the specificity and characteristics of the plant; H. H. Rusby has made an elaborate study of the subject (D. C., Nov., 1900).
Huanuco coca, has been for a long time believed to be obtained from Erythroxylon Coca; this belief is confirmed by Rusby and has been accepted by the Pharmacopoeial authorities. The plant was first described in 1786, in Lamarck's Dictionary, vol. ii, 393.
Truxillo coca is the product of the E. Coca Spruceanum, of Burck; the name "spruceanum" had, however, been used elsewhere before it was suggested by Burck, and in obedience to the ordinary rules of botanical nomenclature it was changed by Rusby, who regards it as a distinct species, to E. Truxillense.
Coca is cultivated in the British East and West Indies, and in Java, and the product is said to appear, in the London markets, under the names of Truxillo coca and Java coca. This coca is entirely distinct from the Truxillo coca of the American market, and does not reach the United States. The coca shrubs of India and Ceylon are the offspring of plants originally sent out from Kew Gardens, which plants were derived from seeds obtained in Huanuco, and were considered by Morris as representing a variety of E. Coca to which he gave the name of E. Novo-Granatense. According to Rusby, however, this plant is a distinct species, and the same as that previously described by Jacquin, from Colombia, under the name of E. carthagenense (the name E. carthagenense not being, as it is held in the Kew Index, a synonym of E. areolatum).
The leaves of the different varieties of coca do not, on the whole, resemble one another at all closely, but are distinguished from most other leaves by a slightly curved line on each side of the midrib, running from the base to the apex. This line has the appearance of a rib, but is really not of this character, having been produced during development by the peculiar folding of the leaf in the bud. The two commercial varieties were very well described in the U. S. Pharmacopoeia VIII as follows:
"Huanuco Coca.—Greenish-brown to clear brown, smooth and slightly glossy, thickish and slightly coriaceous, stoutly and very shortly petioled; blade 2.5 to 7.5 Cm. long and nearly elliptical, with a very short and abruptly narrowed basal portion and a short point, the margin entire; midrib marked above by a slight ridge, very prominent underneath, the remaining venation rather obscure, especially above; underneath, a conspicuous line of collenchyma tissue runs longitudinally on either side of the midrib and about one-third of the distance between it and the margin, the enclosed areola being of a slightly different color from the adjacent surface; odor characteristic; taste bitterish, faintly aromatic, followed by a numbness of the tongue, lips, and fauces.
"Truxillo Coca.—Pale green, thin, brittle and usually much broken, smooth, but not shining, shortly and stoutly petioled; blade 1.6 to 5 Cm. long and one-third to one-half as broad, obovate to oblanceolate, narrowed from near the middle into the petiole, usually with a slight projecting point at the summit, the margin entire; underneath two irregular lines of collenchyma tissue, usually incomplete or obscure, and frequently wanting, run beside the midrib at about one-third the distance from it to the margin; odor more tea-like than that of Huanuco Coca; taste and numbing effect similar." U. S. VIII. "The midrib itself is prolonged into a minute horny apiculus, which, however, is frequently broken off. Most of the epidermal cells of the under surface are seen in transverse section to project in the form of small papillae." Br., 1898.
Chemical Constitution.—In 1853, Wackenroder demonstrated the existence of tannic acid in coca leaves, and in 1859, Stanislaus Martin found in them a peculiar bitter principle, resin, tannin, an aromatic principle, extractive chlorophyll, a substance analogous to theine, and salts of lime. Previous to this (1855) Gardeke had isolated the crystalline alkaloid and given it the name of erythroxyline. Albert Niemann, of Goslar, made the first thorough investigation of the leaves, and gave to the alkaloid the name it now usually bears of cocaine.
Assay. U. S. VIII.—"Coca, in No. 60 powder, ten grammes; chloroform, ether, normal sulphuric acid V.S., ammonia water, distilled water, tenth-normal sulphuric acid V.S., fiftieth-normal potassium hydroxide V.S., cochineal or odeosin T.S., each, a sufficient quantity. Place the Coca in an Erlenmeyer flask, add 50 Cc. of a mixture of chloroform 1 volume and ether 4 volumes and insert the stopper securely. Allow the flask to stand ten minutes, then add 2 Cc. of ammonia water mixed with 3 Cc. of distilled water, and shake the flask well, at frequent intervals, during one hour. Then transfer as much as possible of the contents of the flask to a small percolator which has been provided with a pledge! of cotton packed firmly in the neck, and inserted in a separator containing 6 Cc. of normal sulphuric acid V.S., diluted with 20 Cc. of distilled water. When the liquid has passed through the cotton, pack the Coca firmly in the percolator with the aid of a glass rod, and, having rinsed the flask with 10 Cc. of chloroform-ether mixture, transfer the remaining contents of the flask to the percolator by the aid of several small portions (5 Cc.) of a chloroform-ether mixture, using the same proportions as before, and continue the percolation with successive small portions of the same liquid (in all 50 Cc.). Next, shake the separator well for one minute, after securely inserting the stopper, and when the liquids have completely separated, draw off the acid liquor into another separator. Add to the chloroform-ether mixture 10 Cc. of a sulphuric acid mixture, using the same proportions as before, agitate well and again draw off the acid liquid. Repeat this operation once more, drawing off the acid solution as before into the second separator, introduce a small piece of red litmus paper, add ammonia water until the liquid is distinctly alkaline, and shake out with three successive portions of ether (25, 20, and 15 Cc.). Collect the ether-solutions in a beaker, place it on a water-bath filled with warm water, and allow the ether to evaporate entirely. Dissolve the residue in 3 Cc. of ether, and let this also evaporate completely. To the alkaloidal residue add 4 Cc. of tenth-normal sulphuric acid V.S. and 5 drops of cochineal or iodeosin T.S., then titrate the excess of acid with fiftieth-normal potassium hydroxide V.S. Divide the number of cubic centimeters of fiftieth-normal potassium hydroxide V.S. used, by 5, subtract this number from 4 (the 4 Cc. of tenth-normal sulphuric acid V.S. taken), and multiply the remainder by 0.03 and this product by 10, to obtain the percentage of ether-soluble alkaloids contained in the Coca." U. S. VIII. For methods of assaying coca leaves, see Lyons, Ch. Ph., Sept., 1885; Squibb, Ephem., 1887; Dohme, Proc. A. Ph. A., 1893, 159; Prescott, Organic Analysis; Proc. A. Ph. A., 1895, 268; P. J., 1896, 1901, 222, 254; Ph. Ztg., 1901, 965.
In South America many of the Indians habitually chew the leaf of the coca plant generally mixed with some alkali, as ashes or lime. It is stated on good authority that they will go for days performing hard physical labor without any other food. It is, however, clearly proven that these leaves do not take the place of nutriment, but simply put off the sense of fatigue and hunger. Eventually, however, this habit undermines the health and finally the inveterate excessive coca-chewer can be recognized by his uncertain step, general apathy, sunken eyes surrounded by deep purple aureoles, trembling lips, green and crusted teeth, and excessively fetid breath, with peculiar blackness about the corners of the mouth. An incurable insomnia is apt to be developed, emaciation becomes extreme, dropsy appears, and even death results from a condition of general marasmus. It has been believed that the effects of coca chewing are different from those produced by the alkaloid cocaine and hence it has been by some argued that the coca leaf contains other active principles, but there is no difference between the results of the habit as practised by the South American Indian and the use of the alkaloid by depraved Caucasians, which cannot be readily explained on the ground of difference in the mode of taking the stimulant or racial variation. While there are other active substances present in the coca leaf, it is not manifest that they modify the action of the crude drug materially. For a study of the uses and effects of cocaine, see p. 362, and of tropa-cocaine, see p. 1649.
Coca has a slight bitter tonic effect as well as a stimulant action upon the central nervous system and has been used as a tonic in neurasthenia and other debilitated conditions. The danger of the formation of the habit, however, far outweighs any value the drug may possess, and the use of the crude preparation of coca seems to us hardly justifiable, except under the most extraordinary conditions. The U. S. P., VIII, recognized a fluidextract, the dose of which was from thirty to sixty minims (2-3.9 mils), and a wine the dose of which was two to eight fluidrachms (7.5 to 30 mils).
The Dispensatory of the United States of America, 1918, was edited by Joseph P. Remington, Horatio C. Wood and others.