The potent drug was first prescribed as an anesthetic and a painkiller by doctors who believed that it was a safe substitute for morphine. The drug is a white, crystalline compound that has been processed from the leaves of the coca plant (Erythroxylum coca), a tropical shrub commonly found wild in Peru and Bolivia and cultivated in many other countries. For centuries South American Indians have chewed the coca leaves for pleasure and to help them withstand strenuous working conditions, hunger, and thirst. The cocaine in the leaves produces l ....