Role of the Serotonin 2A Receptor in Psilocybin-induced Altered States of Consciousness

This interventional, crossover trial (n=16) will investigate the role of the serotonin 2A receptor in psilocybin-induced altered states of consciousness, with participants receiving varying doses of psilocybin (5mg, 10mg, 20mg, 40mg) and a 40mg ketanserin pretreatment.

Conducted by University Hospital Basel in Switzerland, the study aims to characterise the subjective effects of psilocybin at different doses using modern psychometric tools, and to examine how plasma concentrations of psilocybin correlate with its effects. The study will also explore the contribution of the serotonin 2A receptor to psilocybin’s influence on consciousness. Participants will undergo randomised and counterbalanced treatments, with at least 10 days between each dose administration.

Researchers will assess the subjective experiences of participants, including mood, perception, and cognition, and correlate these with physiological measures such as heart rate, blood pressure, and sleep patterns. Additionally, the study will measure plasma concentrations of psilocybin and its metabolites to understand the pharmacokinetics of the drug.

Topic Healthy Subjects
Compound Psilocybin
Country Switzerland
Visit trial
Status Planned
Results Published No
Start date 01 February 2025
End date 01 August 2026
Phase Phase I
Design Blinded
Type Interventional
Generation First
Participants 16
Sex All
Age 25- 75
Therapy No

Trial Details

Psilocybin (active compound of "magic mushrooms") is a prototypical psychedelic substance that acts via agonism on serotonin (5-HT) 2A receptors. Psilocybin is rapidly metabolized into its active metabolite psilocin. Psilocybin is currently under investigation as potential treatment for various neuropsychiatric disorders. Psilocybin is also widely used for recreational purposes and as research tool in neuroscience. Besides its current clinical development, a clear characterization of the dose-response relationship of psilocybin is lacking. With the present study the investigators aim to close this knowledge gap by administering low (5mg) to high (40mg) single doses of psilocybin to healthy participants. Besides its agonism on 5-HT2A receptors, psilocin also binds to other receptors and inhibits serotonin transporters (SERT). To this data only few studies have investigated these effects and never at a high dose.

Trial Number NCT06796361

Sponsors & Collaborators

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

Data attribution

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