COCA PLANT

The coca plant is a cultivated shrub, generally found in the Andean Highlands and the northwestern areas of the Amazon in South America. The plant, however, can be grown in many parts of the world and in the early part of the twentieth century much of the cocaine used in medicine was obtained from plants grown in Asia. Of the more than 200 species of the genus Erythroxylon, only E. coca variety ipadu, E. novogranatense, and E. novogranatense variety truxillense contain significant amounts of Cocaine, ranging from 0.6 to 0.8 percent. In addition to cocaine, the leaves of the coca plant contain eleven other Alkaloids, although no others are extracted for their euphorogenic effects.

Coca plants have long histories of use for both their medicinal and stimulant effects. Coca leaves are believed to have been used for well over a millenium, since archeological evidence from Peruvian burial sites of the 6th century a.d. suggests coca use. In fact, ancient Indian legends describe its origin and supernatural powers. The Inca called the coca plant a "gift of the Sun God," and attributed to it many magical functions. The Inca and the other civilizations of the Andes used coca leaves for social ceremonies, religious rites, and medicinal purposes. Because of their energizing property, coca leaves were also used by soldiers during military campaigns or by messengers who traveled long distances in the mountains. Under the Spanish conquest of the sixteenth century, coca plants were systematically cultivated and the custom of chewing coca leaves or drinking coca tea was widely adopted as part of the Indian's daily life in South America. Use of coca leaves as both a medicinal and a psychoactive substance continues to be an integral part of the daily life of the Indians living in the Andean highlands. Substantial societal controls have existed concerning the use of these leaves, and minimal problematic behavior related to use of the coca leaves has been reported.

In the highland areas of Peru and Bolivia, and less frequently, in Ecuador and Colombia, the dried leaves are mixed with lime or ash (called "tocra") and both chewed and sucked. A wad containing 0.4 to 1 ounce (10 to 30 g) of leaf is formed, and daily consumption by coca-leaf chewers is between 1 and 2 ounces (30 and 60 g). The Indian populations in the Amazonean areas, however, crush the dried leaves, mix the powder with an alkaline substance, and chew it. Coca leaves are chewed today in much the same way that they were chewed hundreds of years ago.

Substantial cocaine plasma levels can be attained when coca leaves are chewed along with an alkaline substance, which increases the bioavailability of the drug by changing its pH. Volunteers allowed to chew either the leaf or the powdered form of coca mixed with an alkaline substance reported numbing in the mouth and a generally stimulating effect which lasted an average of approximately an hour after the coca chewing was begun (Holmstedt et al., 1979). This time-course corresponded to the ascending limb of the cocaine plasma-level curve, suggesting that the effect was cocaine-induced. Absorption of cocaine occurs from the buccal mucosa (inner cheek wall) as well as from the gastrointestinal tract after saliva-containing coca juice is swallowed. In fact, plasma concentrations in coca chewers are about what would be predicted if a dose of cocaine equivalent to that in the leaves was administered in a capsule (Paly et al., 1980).

(See also: Bolivia, Drug Use in ; Coca Paste ; Colombia As Drug Source )

BIBLIOGRAPHY

Holmstedt, B., et al. (1979). Cocaine in the blood of coca chewers. Journal of Ethnopharmacology, 1, 69-78.

Paly, D., et al. (1980). Plasma levels of cocaine in native Peruvian coca chewers. In F. R. Jeri (Ed.), Cocaine 1980. Lima: Pacific Press.

Marian W. Fischman