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.
PLoS ONE
August 8, 2012
José Carlos Bouso, Débora González, Sabela Fondevila et al.
313 citations
Regular ayahuasca use over one year is associated with better psychological well-being, mental health, and cognitive performance compared to active controls in non-ayahuasca religions. Users scored higher on Reward Dependence and Self-Transcendence, lower on Harm Avoidance and Self-Directedness, and showed significantly lower psychopathology scores. They performed better on tests of attention, executive function, and working memory (Stroop test, Wisconsin Card Sorting Test, Letter-Number Sequencing). Life attitude measures indicated greater spiritual orientation, purpose in life, and psychosocial well-being. No evidence of psychological maladjustment, mental health deterioration, or cognitive impairment emerged in the ayahuasca group.
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.
Psychopharmacology
March 30, 2006
Jordi Riba, Sergio Romero, Eva Grasa et al.
245 citations
A single oral dose of ayahuasca, equivalent to 1.0 mg DMT per kilogram of body weight, increased blood flow in frontal and paralimbic brain regions of fifteen male volunteers with prior psychedelic experience. Greater perfusion was observed bilaterally in the anterior insula, with stronger effects in the right hemisphere, and in the right anterior cingulate/frontomedial cortex—areas linked to somatic awareness, subjective feeling states, and emotional arousal. Additional increases occurred in the left amygdala/parahippocampal gyrus, a structure involved in emotional processing. These findings indicate that ayahuasca interacts with neural systems central to interoception and emotional processing, suggesting a modulatory role for serotonergic neurotransmission.
Drug and Alcohol Dependence
June 17, 2010
Josep María Fábregas, Débora González, Sabela Fondevila et al.
228 citations
Regular ritual use of ayahuasca, a psychoactive Amazonian tea containing N,N-dimethyltryptamine, does not appear to cause the psychosocial problems typical of other drugs of abuse. In two studies comparing ayahuasca users (56 jungle-based and 71 urban-based) with matched controls, users scored significantly lower on the Addiction Severity Index (ASI) Alcohol Use and Psychiatric Status subscales. Jungle-based users had a higher frequency of past illicit drug use, but this had ceased at examination except for cannabis. At one-year follow-up, abstinence from illicit drugs was maintained except for cannabis in the jungle group. ASI differences remained significant for the jungle group but not the urban group. A time-dependent worsening was observed only in the Family/Social relationships subscale in the urban group.
Psychopharmacology
August 12, 2011
Rafael G. Dos Santos, Eva Grasa, Marta Valle et al.
139 citations
The human pharmacology of ayahuasca, an Amazonian tea containing the psychedelic DMT, was evaluated after repeated doses. In a double-blind, crossover, placebo-controlled trial, nine experienced psychedelic drug users received either a placebo followed by ayahuasca, or two ayahuasca doses four hours apart. DMT plasma concentrations, subjective and neurophysiological effects, and serum prolactin and cortisol were higher after two doses. When effects were adjusted for plasma DMT, no differences appeared for subjective, neurophysiological, autonomic, or immunological measures. A trend toward reduced systolic blood pressure and heart rate, and significant tolerance to growth hormone secretion, were observed after the second dose. No clear tolerance or sensitization occurred in psychological or most physiological variables.
Journal of Clinical Psychopharmacology
October 15, 2011
Rafael G. Dos Santos, Marta Valle, José Carlos Bouso et al.
136 citations
Ayahuasca, an Amazonian psychotropic tea containing DMT and β-carboline alkaloids, produced moderate sympathomimetic effects, significant increases in prolactin and cortisol, and time-dependent changes in immune cell populations in a double-blind crossover trial with 10 healthy volunteers. Pupil dilation occurred with both ayahuasca and amphetamine, but ayahuasca’s effects were milder. Prolactin rose only after ayahuasca, while cortisol peaked higher with ayahuasca than with amphetamine. Lymphocyte subsets shifted similarly for both drugs: CD4 and CD3 percentages decreased, and natural killer cells increased, with maximum changes at 2 hours and return to baseline by 24 hours.
Neuropsychobiology
January 1, 2004
Jordi Riba, P. Anderer, F Jané et al.
131 citations
Ayahuasca, a South American psychotropic plant tea, combines monoamine oxidase-inhibiting β-carboline alkaloids with the psychedelic agent DMT. In a clinical study with 18 volunteers, freeze-dried ayahuasca (0.85 mg DMT/kg body weight) produced dose-dependent changes in spontaneous brain electrical activity, measured via electroencephalography and low-resolution electromagnetic tomography (LORETA). Compared to placebo, ayahuasca decreased power density in alpha-2, delta, theta, and beta-1 frequency bands 60 and 90 minutes after dosing. Power decreases in delta, alpha-2, and beta-1 bands occurred predominantly over the temporo-parieto-occipital junction, while theta power reduced in temporomedial and frontomedial regions. Subjective effects increased across all six scales of the Hallucinogen Rating Scale. The findings suggest involvement of unimodal and heteromodal association cortex and limbic structures in ayahuasca's psychological effects.
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.
Journal of Chromatography B
October 11, 2002
Mercedes Yritia, Jordi Riba, Jordi Ortuño et al.
84 citations
A method to measure the four main alkaloids in ayahuasca (DMT, harmine, harmaline, and tetrahydroharmine) plus two major metabolites (harmol and harmalol) in human plasma is described. DMT is extracted with n-pentane and quantified by gas chromatography with nitrogen-phosphorus detection, achieving 74% recovery, precision and accuracy better than 9.9%, and a limit of quantification of 1.6 ng/ml. The beta-carbolines and metabolites are measured by high-performance liquid chromatography with fluorescence detection after solid-phase extraction, with recoveries above 87%, accuracy and precision better than 13.4%, and limits of quantification from 0.3 to 1.0 ng/ml. The methods allow adequate characterization of the pharmacokinetics of these compounds, including two major metabolites not previously described.
Psychopharmacology
November 20, 2007
Manel J. Barbanoj, Jordi Riba, S. Clos et al.
74 citations
Ayahuasca, a traditional South American psychoactive beverage containing DMT and beta-carboline alkaloids, did not impair subjective sleep quality or disrupt sleep initiation and maintenance in 22 healthy male volunteers, unlike d-amphetamine which delayed sleep onset, disrupted maintenance, and reduced deep sleep. Both ayahuasca and d-amphetamine reduced REM sleep duration and increased high-frequency EEG power during stage 2 sleep. However, while d-amphetamine decreased slow-wave sleep power in the first night cycle (an indicator of sleep pressure), ayahuasca enhanced it. The findings suggest that serotonergic psychedelics interact with brain circuits regulating REM and slow-wave sleep.
Psychopharmacology
December 1, 2002
Jordi Riba, Antoni Rodrı́guez-fornells, Manel J. Barbanoj
71 citations
Ayahuasca, a South American psychotropic plant tea containing the psychedelic DMT and beta-carboline alkaloids, produces diverging effects on two measures of neural gating. In a double-blind, crossover trial with 18 healthy volunteers who had prior psychedelic experience, ayahuasca caused significant dose-dependent reductions in P50 suppression, an operational measure of sensory gating. However, no significant effects were found on prepulse inhibition of startle (PPI), a measure of sensorimotor gating, or on startle response habituation at any prepulse-to-pulse interval tested. These findings indicate that ayahuasca disrupts sensory gating while leaving sensorimotor gating unaffected at the doses administered.
Journal of Psychoactive Drugs
June 1, 2005
Jordi Riba, Manel J. Barbanoj
58 citations
Since 1999, a research team at the Autonomous University of Barcelona has conducted clinical studies administering ayahuasca to healthy volunteers. The work addresses two needs: systematically establishing the safety and pharmacological profile of ayahuasca, a complex brew of active compounds, given growing interest in traditional indigenous practices; and advancing understanding of how psychedelics modify higher-order cognitive processes, which remains incomplete despite known molecular and electrophysiological effects. The article reviews methodological aspects, basic clinical findings, current laboratory research, and outlines two planned studies to further knowledge of ayahuasca's pharmacology.
Neuropsychobiology
January 1, 2004
Nikolas Coupland, Tai-Jui Chen, Terence O'Donnell et al.
1 citation
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