Pharmacokinetics of Hoasca alkaloids in healthy humans

N,N-Dimethyltryptamine (DMT), harmine, harmaline and tetrahydroharmine (THH ) are the characteristic alkaloids found in Amazonian sacraments known as h oasca, ayahuasca, and yaje. Such beverages are characterized by the presenc e of these three harmala alkaloids, where harmine and harmaline reversibly inhibit monoamine oxidase A (MAO-A) while tetrahydroharmine weakly inhibits the uptake of serotonin. Together, both actions increase central and perip heral serotonergic activity while facilitating the psychoactivity of DMF. T hough the use of such 'teas' has be known to western science for over 100 y ears, little is known of their pharmacokinetics. In this study, hoasca was prepared and administered in a ceremonial context. All four alkaloids were measured in the tea and in the plasma of 15 volunteers, subsequent to the i ngestion of 2 mi hoasca/kg body weight, using gas (GC) and high pressure li quid chromatographic (HPLC) methods. Pharmacokinetic parameters were calcul ated and peak times of psychoactivity coincided with high alkaloid concentr ations, particularly DMT which had an average T-max of 107.5 +/- 32.5 min. While DMT parameters correlated with those of harmine, THH showed a pharmac okinetic profile relatively independent of harmine's, (C) 1999 Elsevier Sci ence Ireland Ltd. All rights reserved.