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HealthyPhase 1LPMNCT04227756

Comparative Acute Effects of LSD, Psilocybin and Mescaline

A Phase 1 study testing LSD, Psilocybin and Mescaline in people with Healthy, run by University Hospital, Basel, Switzerland at 1 site in Switzerland.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial 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. Read more about this study

Who is it for?
Ages 25 to 65 yearsHealthy volunteers can take part
Conditions the study is for
Healthy
What is being tested?
LSD, Psilocybin and Mescaline
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
32 participants
Where
1 siteSwitzerland
Study dates
19 May 2020to 2 Sep 2022
Phase
Phase 1
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 25 to 65 years
  • All sexes
  • Healthy volunteers accepted
  • Adult, Older adult

Who may be able to join

  • Age between 25 and 65 years old
  • Sufficient understanding of the German language
  • Understanding of procedures and risks associated with the study
  • Willing to adhere to the protocol and signing of the consent form
  • Willing to refrain from the consumption of illicit psychoactive substances during the study
  • Abstaining from xanthine-based liquids from the evenings prior to the study sessions to the end of the study days
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  • Willing not to operate heavy machinery within 48 hours after substance administration
  • Willing to use double-barrier birth control throughout study participation
  • Body mass index between 18-29 kg/m2

Who cannot join

  • Chronic or acute medical condition
  • Current or previous major psychiatric disorder
  • Psychotic disorder or bipolar disorder in first-degree relatives
  • Hypertension (>140/90 mmHg) or hypotension (SBP<85 mmHg)
  • Hallucinogenic substance use (not including cannabis) more than 20 times or any time within the previous two months
  • Pregnancy or current breastfeeding
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  • Participation in another clinical trial (currently or within the last 30 days)
  • Use of medication that may interfere with the effects of the study medication
  • Tobacco smoking (>10 cigarettes/day)
  • Consumption of alcoholic beverages (>20 drinks/week)
  • Failure of MRI-related criteria

Trial locations and contacts

1 site in 1 country.

Switzerland1 site

  • University Hospital Basel, Clinical Trial Unit

    Basel, Canton of Basel-City, 4031

Other trials in Switzerland

About this study

Official title: Comparative Acute Effects of LSD, Psilocybin and Mescaline in a Random-Order Placebo-Controlled Cross-Over Study in Healthy Subjects

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.

Read the detailed description

LSD (lysergic acid diethylamide), psilocybin (the active substance in "magic mushrooms") and mescaline (the active substance in Peyote and San Pedro cacti) are serotonergic hallucinogens widely used for recreational and/or ethnomedical purposes. LSD, psilocybin and mescaline are thought to induce prototypical psychedelic effects primarily via stimulation of the 5-HT2A receptor. However, there are differences in their molecular structures (LSD: ergoline, psilocybin: tryptamine; mescaline: phenethylamine)and receptor activation profiles which may induce different subjective effects. To date, there are no modern studies comparing these three substances 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. The main objective of this study is to determine whether LSD, psilocybin and mescaline produce qualitatively similar subjective alterations of mind and associated brain activity patterns despite their unique receptor activation profiles. The study investigates psychological (psychometry), physiological and neuronal (magnetic resonance imaging) variables. The LPM-Study provides insight into the acute effects profiles of three serotonergic hallucinogens. It will enhance the understanding of psychedelic-induced altered states of consciousness in humans and will be relevant for the fields of psychiatry, psychology, and forensic toxicology.

Conditions
Healthy
Being tested
LSD, Psilocybin, Mescaline, Placebo

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • LSDDrug

    LSD 0.1 mg per os, single dose OR Psilocybin 20 mg per os, single dose OR Mescaline 300 mg per os, single dose OR Placebo

  • PsilocybinDrug

    Psilocybin 20 mg per os, single dose

  • MescalineDrug

    Mescaline 300 mg or 500 mg per os, single dose

  • PlaceboOther

    Placebo (Mannitol)

Study groups in NCT04227756
Study groupRoleWhat they receive
LSD-100ExperimentalCross-over within-subject design with all treatment conditions, separated by a wash-out phase of at least 10 days
Receives: Drug: LSD
Psilocybin-20Active comparatorCross-over within-subject design with all treatment conditions, separated by a wash-out phase of at least 10 days
Receives: Drug: Psilocybin
Mescaline-300/500Active comparatorCross-over within-subject design with all treatment conditions, separated by a wash-out phase of at least 10 days
Receives: Drug: Mescaline
PlaceboPlacebo comparatorCross-over within-subject design with all treatment conditions, separated by a wash-out phase of at least 10 days
Receives: Other: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. 5 Dimensions of Altered States of Consciousness (5D-ASC)

    5D-ASC subscale ratios

    Measured: 18 months

  2. fMRI resting state functional connectivity (RSFC)

    Spontaneous low-frequency fluctuations in BOLD signal during resting state

    Measured: 18 months

Secondary outcomes (18)

  1. Visual Analog Scale (VAS)

    Assesses the intensity and duration of subjective effects on a scale from 0% - 100% with higher scores representing more intense effects

    Measured: 18 months

  2. States of Consciousness questionnaire (SCQ)

    Assesses the emergence and intensity of phenomenons occurring in altered states of consciousness on a 6-point Likert scale ranging from 0 ("not at all") to 5 ("extremely")

    Measured: 18 months

  3. Blood pressure

    Assessment of sympathetic activation

    Measured: 18 months

  4. Heart rate

    Assessment of sympathetic activation

    Measured: 18 months

  5. Body temperature

    Assessment of sympathetic activation

    Measured: 18 months

  6. Pupil size

    Assessment of sympathetic activation

    Measured: 18 months

  7. Drug plasma levels

    Plasma levels of investigational drugs

    Measured: 18 months

  8. Oxytocin levels

    Levels of oxytocin in blood plasma

    Measured: 18 months

  9. Blood-derived neurotrophic factor (BDNF)

    Blood plasma levels of BDNF

    Measured: 18 months

  10. Renal clearance values

    Renal clearance values of investigational drugs through urine recovery

    Measured: 18 months

  11. NEO-Five-Factor-Inventory (NEO-FFI)

    Assesses personality traits

    Measured: 18 months

  12. Freiburger Persönlichkeitsinventar (FPI)

    Assesses personality traits

    Measured: 18 months

  13. Saarbrücker Persönlichkeitsfragebogen (SPF)

    Assesses personality traits

    Measured: 18 months

  14. Adjective Mood Rating Scale (AMRS)

    Assesses the occurrence and intensity of 60 moods on a 4-point Likert scale ranging from "not at all" to "extremely"

    Measured: 18 months

  15. Mysticism Scale (MS)

    Assesses the occurrence and intensity of mystical qualities in altered states of consciousness on a 9-point Likert scale ranging from -4 ("extremely inapplicable") to +4 ("extremely applicable"), with higher values indicating a more intense experience

    Measured: 18 months

  16. Elliot Humility Scale (EHS)

    Assesses the personality trait humility through 13 items on a 5-point Likert scale ranging from "strongly disagree" to "strongly agree"

    Measured: 18 months

  17. Jankowski Humility Scale (JHS)

    Assesses the personality trait humility through 18 items on a 5-point Likert scale ranging from "not at all" to "strongly"

    Measured: 18 months

  18. Arnett Inventory of Sensation Seeking (AISS-d)

    Assesses personality traits

    Measured: 18 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted14 Jan 2020
  2. Study start19 May 2020
  3. Primary completion2 Sep 2022
  4. Study completion2 Sep 2022

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 1
Primary purpose
Basic science
Allocation
Randomised
Intervention model
Crossover
Model description
Double-blind, placebo-controlled, 4-period cross-over design with four treatment conditions
Masking
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
32 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT04227756
Sponsor's protocol ID
BASEC 2019-02023
Acronym
LPM
Status last verified
Jan 2024
First submitted
7 Jan 2020
Last updated
24 Jan 2024
Results posted
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
No

Publications

  • Mueller L, Klaiber A, Ley L, Becker AM, Thomann J, Luethi D, Schmid Y, Liechti ME. Pharmacokinetics, Pharmacodynamics, and Urinary Recovery of Oral Mescaline Hydrochloride in Healthy Participants. Clin Pharmacokinet. 2025 Oct;64(10):1495-1506. doi: 10.1007/s40262-025-01544-x. Epub 2025 Jul 14.

    PubMed 40658345

  • Ley L, Holze F, Arikci D, Becker AM, Straumann I, Klaiber A, Coviello F, Dierbach S, Thomann J, Duthaler U, Luethi D, Varghese N, Eckert A, Liechti ME. Comparative acute effects of mescaline, lysergic acid diethylamide, and psilocybin in a randomized, double-blind, placebo-controlled cross-over study in healthy participants. Neuropsychopharmacology. 2023 Oct;48(11):1659-1667. doi: 10.1038/s41386-023-01607-2. Epub 2023 May 25.

    PubMed 37231080

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing LSD, Psilocybin and Mescaline in people with Healthy, run by University Hospital, Basel, Switzerland at 1 site in Switzerland.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 9 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 24 Jan 2024. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

5 Dimensions of Altered States of Consciousness (5D-ASC) (time frame: 18 months). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT04227756, which also lists 2 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 24 Jan 2024.

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