Comparative Acute Effects of R-MDMA and S-MDMA in Healthy Participants (R-S-)

This randomised, triple-blind, placebo-controlled Phase I crossover trial (n=24) will compare the acute effects of two enantiomers of MDMA—R-MDMA (300mg) and S-MDMA (100mg)—in healthy adult participants.

The study, led by University Hospital Basel in Switzerland, aims to clarify the distinct pharmacological and subjective effects of each enantiomer of MDMA, which are mirror-image molecules of the same compound. R-MDMA is thought to act more directly on serotonin 5-HT2A receptors and promote prosocial effects with fewer stimulant properties, while S-MDMA is believed to be more associated with stimulant effects through the release of dopamine, norepinephrine, serotonin, and oxytocin.

Participants will undergo three separate dosing sessions (R-MDMA, S-MDMA, and placebo) in a triple-blind crossover design. Outcomes will include subjective experiences (measured repeatedly each session using Visual Analogue Scales), vital signs, hormone levels (including oxytocin and prolactin), and personality traits. The researchers hope this study will inform future therapeutic applications of MDMA by understanding how each enantiomer contributes to the full drug experience and its safety profile. The trial is expected to run from May 2025 to November 2026.

Topic Healthy Subjects
Compound MDMA Placebo
Country Switzerland
Visit trial

Trial Details



Trial Number

Sponsors & Collaborators

University of Basel
The University of Basel Department of Biomedicine hosts the Liechti Lab research group, headed by Matthias Liechti.

Data attribution

A large set of the trials in our database are sourced from ClinicalTrials.gov (CTG). We have modified these post to display the information in a more clear format or to correct spelling mistakes. Our database in actively updated and may show a different status (e.g. completed) if we have knowledge of this update (e.g. a published paper on the study) which isn't reflected yet on CTG. If a trial is not sourced from CTG, this is indicated on this page and you can follow the link to the alternative source of information.