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

Recruiting now · Phase 1 · Has a placebo group

Conditions studied: Healthy

In brief

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.

Key facts

Study ID

NCT06796361

Run by

University Hospital, Basel, Switzerland

People needed

16

Starts

2025-04-21

Expected to finish

2026-08-01

Last updated by the study team

2025-05-28

Who can join

Age: 25 and older, up to 75. Sex: any. Healthy volunteers: accepted.

You may qualify if…

• Age between 25 and 75 years.
• Sufficient understanding of the German language.
• Understanding the procedures and the risks that are associated with the study.
• Participants must be willing to adhere to the protocol and sign the consent form.
• Participants must be willing to refrain from taking illicit psychoactive substances during the study (not including cannabis).
• Participants must be willing not to drive a traffic vehicle or to operate machines within 48 h after substance administration.
• Women of childbearing potential must be willing to use effective birth-control throughout study participation

You may not qualify if…

• Chronic or acute medical condition, including a history of seizures.
• Body mass index 18-29.9 kg/m2
• Current or previous major psychiatric disorder (e.g. psychotic disorders, mania / hypomania, anxiety disorders).
• Psychotic or bipolar disorder in first-degree relatives, not including psychotic disorders secondary to an apparent medical reason, e.g., brain injury, dementia, or lesions of the brain.
• Hypertension (SBP>140/90 mmHg) or hypotension (SBP<85 mmHg)
• Psychedelic substance use (with the exception of cannabis) more than 20 times or any time within the previous two months
• Pregnant or nursing women.
• Participation in another clinical trial (currently or within the last 30 days).
• Use of medications that may interfere with the effects of the study medications (any psychiatric medications and any medication with known to interact with the study substances).
• Tobacco smoking (>10 cigarettes/day).
• Consumption of alcoholic drinks (>15 drinks / week).
• Body weight < 45 kg.

Where it is running

• Clinical Trial Unit — Basel, Canton of Basel-City, Switzerland (enrolling)

Full record on ClinicalTrials.gov

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