Pharmacokinetics of Hoasca alkaloids in healthy humans.

After ingesting 2 ml/kg of hoasca (ayahuasca) tea, the four main alkaloids—DMT, harmine, harmaline, and tetrahydroharmine (THH)—were measured in the plasma of 15 volunteers. Peak psychoactive effects coincided with high alkaloid concentrations, especially DMT, which reached its maximum concentration at an average of 107.5 minutes. DMT's pharmacokinetics correlated with harmine's, while THH showed a relatively independent profile. The tea's harmala alkaloids inhibit monoamine oxidase A and weakly inhibit serotonin uptake, increasing serotonergic activity and enabling DMT's psychoactivity.

Study at a glance

Abstract

N,N-Dimethyltryptamine (DMT), harmine, harmaline and tetrahydroharmine (THH) are the characteristic alkaloids found in Amazonian sacraments known as hoasca, ayahuasca, and yajè. Such beverages are characterized by the presence 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 peripheral serotonergic activity while facilitating the psychoactivity of DMT. Though the use of such 'teas' has be known to western science for over 100 years, 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 ingestion of 2 ml hoasca/kg body weight, using gas (GC) and high pressure liquid chromatographic (HPLC) methods. Pharmacokinetic parameters were calculated and peak times of psychoactivity coincided with high alkaloid concentrations, particularly DMT which had an average Tmax of 107.5 +/- 32.5 min. While DMT parameters correlated with those of harmine, THH showed a pharmacokinetic profile relatively independent of harmine's.