Journal of Pharmacology and Experimental Therapeutics
June 18, 2003
Jordi Riba, Marta Valle, Gloria Urbano et al.
383 citations
Ayahuasca, a South American psychedelic beverage combining DMT with MAO-inhibiting beta-carboline alkaloids, produces significant subjective perceptual and mood effects peaking 1.5 to 2 hours after oral administration. In a double-blind placebo-controlled trial with 18 experienced psychedelic users, doses of 0.6 and 0.85 mg DMT/kg increased diastolic blood pressure by 9 mm Hg at the high dose, while systolic pressure and heart rate rose modestly but not significantly. Peak DMT blood concentrations (Cmax) were 12.14 ng/ml and 17.44 ng/ml for low and high doses, respectively, coinciding with subjective effect peaks. Urinary normetanephrine increased, but deaminated monoamine metabolites did not decrease, and harmine plasma levels were negligible, suggesting harmine acts primarily in the gastrointestinal tract and liver to prevent DMT breakdown and allow its entry into the brain.
Psychopharmacology
February 22, 2001
Jordi Riba, Antoni Rodrı́guez-fornells, Gloria Urbano et al.
302 citations
Ayahuasca, a South American psychoactive beverage containing DMT, produced dose-dependent psychological effects in six healthy male volunteers with prior experience. Encapsulated freeze-dried ayahuasca at doses of 0.5, 0.75, and 1.0 mg DMT/kg body weight increased scores on hallucinogen rating scales, addiction research inventory scales, and visual analogue scales for liking, good effects, and high. Effects began within 30-60 minutes, peaked at 60-120 minutes, and resolved by 240 minutes. The tea was well tolerated cardiovascularly, though nausea and altered physical sensations were common. Five volunteers found the experience pleasant; one had an intensely dysphoric reaction with anxiety and withdrew. Ayahuasca induced perceptual, affective, cognitive, and somatic changes of longer duration and milder intensity than intravenous DMT.
British Journal of Clinical Pharmacology
June 1, 2002
Jordi Riba, P. Anderer, Adelaida Morte et al.
126 citations
Ayahuasca, a psychoactive tea from South America, produces measurable changes in brain electrical activity that parallel its subjective psychedelic and stimulant effects. In a double-blind crossover trial, 18 volunteers received low and high doses of freeze-dried ayahuasca. Electroencephalography recordings from baseline to eight hours showed dose-dependent decreases in absolute power across all frequency bands, especially theta, and decreases in relative delta and theta power with increases in beta power. Effects began within 15–30 minutes, peaked between 45 and 120 minutes, and returned to baseline by four to six hours. The pattern resembles that of other serotonergic psychedelics and supports the role of 5-HT2 and dopamine D2 receptor activation.