Ethnopharmacology of kratom and the Mitragyna alkaloids.

sirs, Mitragyna speciosa Korth. (“kratom”, “biak”) is a Southeast Asian tree, the leaves of which provide several alkaloids of considerable interest and seemingly contradictory properties. In 1836, Low (Burkill, 19351 described the use of kratom by native Malayans as an opium substitute when opium itself was unavailable or unaffordable. Holmes (18951 identified kratom as M. speciosa and its use as a substitute for opium was again noted. In 1907, Wray described how it may be smoked, chewed or drunk as an infusion with opium-like effects regardless of the method of administration (Wray, 1907al. Large doses were claimed to result in stupor while frequent indulgence led to an “indolent life”. He expressed the hope that an active principle would soon be isolated and its usefulness to medicine assessed (Wray, 1907bl. Samples of the leaves were sent to the University of Edinburgh where, 14 years later, Field (19211 isolated two new alkaloids: mitragynine (from M. speciosa) and mitraversine (from M. pu~tifoZial. Burkill (19301 recorded the uses of kratom as wound poultice, cure for fever and suppressor of the opiate withdrawal syndrome. The first formal pharmacological investigations were carried out at the University of Cambridge. Grewal 0932al performed a series of experiments on animal tissues and found mitragynine to be a central nervous system stimulant rather than depressant. He wrote that in this respect it resembled cocaine and noted widespread use in Thailand to increase work efficiency, tolerance of hot sun and that addicts were claimed to be thin with distended stomachs, unhealthy complexions, dark lips and dry skin (Grewal, 1932b). Grewal subsequently administered mitragynine to five men and again observed a cocaine-like effect, discovering that in the leaf form much less alkaloid was required. Fifty milligrams of pure mitragynine acetate produced nausea and vomiting in some subjects. The 1930s saw increasing French interest in M. africana (Raymond-Hamet,