CompletedPhase 1

Comparative Acute Effects of LSD, Psilocybin and Mescaline

NCT04227756 · LPM · University Hospital, Basel, Switzerland

Closed to entry

Status

Not accepting participants

Phase 1

Phase

Target enrolment

Study sites

Outside the US

What it is testing

Summary

LSD, psilocybin and mescaline are widely used for recreational and ethnomedical purposes. All three substances are thought to induce prototypical psychedelic effects primarily via stimulation of the 5-HT2A receptor. However, there are differences in the substances' molecular structures and receptor activation profiles which may induce differential subjective effects. To date, there are no modern studies comparing LSD, psilocybin and mescaline directly within the same clinical study and research subjects using validated psychometric tools. Therefore, the LPM-Study compares the acute effects of LSD, psilocybin, mescaline and placebo in a double-blind, placebo-controlled, 4-period cross-over design with four treatment conditions: 1) 100 μg LSD, 2) 20 mg psilocybin, 3) 300 or 500 mg mescaline, and 4) placebo.

Summary as written by the trial’s own sponsor and published on ClinicalTrials.gov API v2. It is the sponsor’s description, reproduced unedited, not an assessment by this site.

What counts as success

Primary outcome measures

5 Dimensions of Altered States of Consciousness (5D-ASC)
Measured over 18 months
fMRI resting state functional connectivity (RSFC)
Measured over 18 months

A trial succeeds or fails on its primary outcome, declared in advance. Everything else it reports is secondary by definition.

Who can take part

Eligibility, as published

25 Years to 65 Years

Ages

All

Sex

Accepted

Healthy volunteers

Inclusion Criteria: 1. Age between 25 and 65 years old 2. Sufficient understanding of the German language 3. Understanding of procedures and risks associated with the study 4. Willing to adhere to the protocol and signing of the consent form 5. Willing to refrain from the consumption of illicit psychoactive substances during the study 6. Abstaining from xanthine-based liquids from the evenings prior to the study sessions to the end of the study days 7. Willing not to operate heavy machinery within 48 hours after substance administration 8. Willing to use double-barrier birth control throughout study participation 9. Body mass index between 18-29 kg/m2 Exclusion Criteria: 1. Chronic or acute medical condition 2. Current or previous major psychiatric disorder 3. Psychotic disorder or bipolar disorder in first-degree relatives 4. Hypertension (\>140/90 mmHg) or hypotension (SBP\<85 mmHg) 5. Hallucinogenic substance use (not including cannabis) more than 20 times or any time within the previous two months 6. Pregnancy or current breastfeeding 7. Participation in another clinical trial (currently or within the last 30 days) 8. Use of medication that may interfere with the effects of the study medication 9. Tobacco smoking (\>10 cigarettes/day) 10. Consumption of alcoholic beverages (\>20 drinks/week) 11. Failure of MRI-related criteria

Where

1 study site

Facility	City	Region	Country
University Hospital Basel, Clinical Trial Unit	Basel	Canton of Basel-City	Switzerland

On the registry

Contact the trial directly

This site does not enrol anyone and is not involved in this trial. To ask about taking part, use the sponsor’s own contact details on the official registry record, which is also where the most current version of everything above lives.

Before you do, the preparation checklist lists what a site will ask you on a first call and what is worth asking them. It is free and collects nothing.

NCT04227756 on ClinicalTrials.gov →

Last updated in the registry 2024-01-24. Registry records change; this page reflects the data build of 2026-08-25.

Where this trial sits

Substance

All 48 trials from University Hospital, Basel, Switzerland →