Pharmacokinetics of Hoasca alkaloids in healthy humans.
Journal of ethnopharmacology June 1, 1999 J C Callaway, D J McKenna, C S Grob et al.
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.