Acute Effects of MDMA Co-administration on the Response to Psilocybin in Healthy Subjects (MDMA-Psilo)

This double-blind, placebo-controlled, crossover trial (n=24) will investigate the acute effects of psilocybin (20mg) when co-administered with MDMA (100mg) in healthy adults.

The study, conducted by University Hospital Basel in Switzerland, aims to determine whether MDMA enhances the positive effects of psilocybin—such as mood elevation, empathy, and trust—while reducing potential negative effects like anxiety and paranoia.

Participants will take part in four different sessions, receiving either psilocybin alone, MDMA alone, both substances together, or a placebo. The study will measure subjective experiences using various psychological scales, as well as physiological responses such as heart rate, blood pressure, and body temperature. Researchers will also assess blood plasma levels of both drugs and their metabolites. This Phase I study, led by Professor Dr. Matthias Liechti, is expected to run from April 2025 to July 2026.

Trial Details

The acute subjective effects of serotonin (5-HT)2A receptor stimulation with psilocybin in humans are mostly positive. However, negative effects such as anxiety, paranoid thinking, or loss of trust towards other people are common effects, depending on the dose administered, the personality traits of the person consuming it (set), or the environment in which psilocybin is taken (setting). Negative psychedelic effects may cause acute distress to the subject and acute anxiety has been linked to less favorable long-term outcomes in patients experimentally treated with psilocybin or similar substances for the treatment of depression. The 5-HT and oxytocin releaser 3,4-methylenedioxymethamphetamine (MDMA) reliably induces positive mood, euphoria, comfort, empathy, and feelings of trust. If administered in combination with psilocybin, MDMA may increase positive subjective drug effects including positive mood, empathy, and trust and reduce negative emotions and anxiety associated with psilocybin and overall produce a more positive over negative experience. The present study will assess subjective and autonomic effects of psilocybin alone and in combination with MDMA.

Trial Number NCT06884514

Data attribution

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