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HealthyPhase 1LPDNCT06899334

Direct Comparison of Altered States of Consciousness Induced by LSD, Psilocybin, and DMT in Healthy Participants

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

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

The primary objective of this study is to determine whether equivalent moderately high doses of LSD, psilocybin, and DMT produce qualitatively similar peak effects when the effect duration is standardized with ketanserin. Read more about this study

Who is it for?
Ages 25 years and olderHealthy volunteers can take part
Conditions the study is for
Healthy
What is being tested?
LSD, Psilocybin and DMT
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
24 participants
Where
1 siteSwitzerland
Study dates
1 Apr 2025to 1 Aug 2026
Phase
Phase 1
Are there results?
Not yet: the study is under way

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 years and older
  • All sexes
  • Healthy volunteers accepted
  • Adult, Older adult

Who may be able to join

  • Good 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
  • Willing not to operate heavy machinery within 48 h after administration of a study substance
  • Willing to use effective birth control throughout study participation
  • Body mass index 17 - 34.9 kg/m2

Who cannot join

  • Relevant chronic or acute medical condition
  • Current or previous major psychiatric disorder (e.g. psychotic disorder)
  • Psychotic disorder or bipolar disorder in first-degree relatives
  • Hypertension (SBP>140/90 mmHg) or hypotension (SBP<85 mmHg)
  • Bradycardia (< 45 bpm)
  • Prolonged QTc interval (males: >450 ms, females: >470 ms)
Show all 13Show fewer
  • AV block II° (Mobitz type and Webckebach type) and III°
  • Hallucinogenic substance use (not including cannabis) more than 20 times or any time within the previous two months
  • Pregnancy or current breastfeeding
  • 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)
  • Excessive consumption of alcoholic beverages (>15 drinks/week)

Trial locations and contacts

1 site in 1 country. Contact the study team or a site near you to ask about taking part.

Matthias E Liechti, Prof. Dr. MD contact

61 328 68 68 ext. +41

matthias.liechti@usb.ch

Mélusine Humbert-Droz, MSc contact

61 328 48 19 ext. +41

melusine.humbert-droz@usb.ch

Switzerland1 site, 1 recruiting

  • University Hospital

    Basel, 4056

    Matthias E Liechti, Prof. Dr. MD, 61 328 68 68 ext. +41, matthias.liechti@usb.ch

    Mélusine Humbert-Droz, MSc, 61 328 48 19 ext. +41, melusine.humbert-droz@usb.ch

    Recruiting

Other trials in Switzerland

About this study

Official title: Direct Comparison of Altered States of Consciousness Induced by LSD, Psilocybin, and DMT in a Randomized, Placebo-controlled, Cross-over Trial in Healthy Participants (LPD-Study)

The primary objective of this study is to determine whether equivalent moderately high doses of LSD, psilocybin, and DMT produce qualitatively similar peak effects when the effect duration is standardized with ketanserin. A DMT infusion mimicking oral LSD and psilocybin administrations will be tested, as well as intravenously administered ketanserin.

Read the detailed description

Lysergic acid diethylamide (LSD), psilocybin, and N,N-dimethyltryptamine (DMT) are serotonergic hallucinogens (psychedelics) and currently investigated as therapeutic tools for the treatment of various psychiatric disorders. They are usually administered in a dose range which induces an alteration of consciousness via the stimulation of the serotonin (5-HT)2A receptor. However, there are differences in the receptor activation profiles between the three substances that may induce different subjective effects. Moreover, they exhibit different pharmacokinetic qualities. In comparative studies of LSD and psilocybin blinding was impaired by the different duration of subjective effects. This study aims to ensure blinding by ending all experiences at the same time with the 5HT2A antagonist ketanserin. Moreover, no study has yet directly compared DMT to LSD and psilocybin. The DMT infusion will be modeled in accordance with the course of an oral LSD and psilocybin administration. Therefore, the LPD-study compares the acute and subacute effects of LSD, psilocybin, and DMT while standardizing the time course and the duration of action for all substances.

Conditions
Healthy
Being tested
LSD, Psilocybin, DMT, Placebo
Keywords
Psychedelics, LSD, Psilocybin, DMT

What participants receive

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

  • LSDDrug

    A moderate to high oral dose of 150 µg LSD will be administered followed by 20 mg intravenous ketanserin after 3 h

  • PsilocybinDrug

    A moderate to high oral dose of 30 mg psilocybin will be administered followed by 20 mg intravenous ketanserin after 3 h

  • DMTDrug

    A moderate to high, dose-escalating, intravenous infusion up to 2 mg/min DMT will be administered followed by 20 mg intravenous ketanserin after 3 h

  • PlaceboDrug

    An oral and an intravenous placebo will be administered followed by 20 mg intravenous ketanserin after 3 h

Study groups in NCT06899334
Study groupRoleWhat they receive
LSDExperimental150 µg lysergic acid diethylamide followed by 20 mg ketanserin intravenously after 3 h
Receives: Drug: LSD
PsilocybinExperimental30 mg Psilocybin followed by 20 mg ketanserin intravenously after 3 h
Receives: Drug: Psilocybin
DMTExperimentalDose escalating DMT intravenous infusion up to 2 mg/min followed by 20 mg ketanserin intravenously after 3 h
Receives: Drug: DMT
PlaceboPlacebo comparatorPlacebo followed by 20 mg ketanserin intravenously after 3 h
Receives: Drug: Placebo

What is being measured

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

  1. 1. Altered state of consciousness profile (5D-ASC)

    5 Dimensions of Altered States of Consciousness (5D-ASC) consisting of 94 items to be rated on a visual analog scale (0-100 mm), with higher values indicating stronger effects.

    Measured: 18 months

Secondary outcomes (17)

  1. Subjective effects (VASs)

    Visual Analog Scales assessing the intensity and duration of subjective effects on a scale from 0 - 100 percent with higher scores representing more intense effects.

    Measured: 18 months

  2. Mystical-type experiences (PES)

    This 100-item Psychedelic Experience Questionnaire/Scale (PES100) is rated on a six-point scale (0 indicating "not at all" and 5 indicatin "extremely"). It comprises distractor items as well as subscales which measure mystical-type effects.

    Measured: 18 months

  3. Mystical-type experiences (PAE-PS-ext)

    This Phenomenological-Autobiographical-Existential Psychedelic Scale extended (PAE-PS-ext) questionnaire rates psychedelic experiences with a focus on phenomenological, autobiographical, and existential psychedelic experiences (scale from 0 - 100 percent with higher scores representing more intense effects).

    Measured: 18 months

  4. 3. Emotional breakthrough inventory (EBI+)

    This 18-item questionnaire is a visual analog scale (from 0 - 100 percent with higher scores representing more intense effects) assessing emotional breakthrough throughout the study sessions.

    Measured: 18 months

  5. Plasma levels of LSD

    Assessed 20 times on each study day via blood samples

    Measured: 18 months

  6. Plasma levels of psilocybin

    Assessed 20 times on each study day via blood samples

    Measured: 18 months

  7. Plasma levels of DMT

    Assessed 20 times on each study day via blood samples

    Measured: 18 months

  8. Plasma levels of ketanserin

    Assessed 20 times on each study day via blood samples

    Measured: 18 months

  9. Plasma levels of oxytocin

    Assessed 2 times on each study day via blood samples

    Measured: 18 months

  10. Plasma levels of prolactin

    Assessed 2 times on each study day via blood samples

    Measured: 18 months

  11. Plasma levels of cortisol

    Assessed 2 times on each study day via blood samples

    Measured: 18 months

  12. Autonomic effects I

    Assessed 16 times on each study day via systolic and diastolic blood pressure

    Measured: 18 months

  13. Autonomic effects II

    Assessed 16 times on each study day via heart rate

    Measured: 18 months

  14. Autonomic effects III

    Assessed one time at screening visit and twice on each study day via ECG (QT-time)

    Measured: 18 months

  15. Adverse effects (B-LR)

    The 2011 revised Beschwerden-Liste (B-LR) consists of a 40-item list covering a wide variety of symptoms and complaints that are answered with a four-point intensity-scoring ranging from 0 indicating "not at all" to 3 indicating "strong."

    Measured: 18 months

  16. Adverse effects (SPSI)

    The Swiss Psychedelic Side Effects Inventory evaluates side effects associated with psychedelics using a binary "yes or no" approach. Severity is recorded using a three-point intensity scale ranging from 1 indicating "light" to 3 indicating "strong." The impact is recorded using a five-point scale ranging from -2 "very disadvantageous" to +2 "very advantageous." The relation to the drug is recorded using a five-point scale ranging from 0 indicating "unknown" to 4 indicating "certain."

    Measured: 18 months

  17. Adverse Events (AE)

    Any report of adverse events will be recorded on a AE-Form.

    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 posted27 Mar 2025
  2. Study start1 Apr 2025 (estimated)
  3. Primary completion1 Aug 2026 (estimated)
  4. Study completion1 Aug 2026 (estimated)

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
4-period, random order, placebo-controlled, double-blind cross-over study
Masking
Triple blind
Who is masked
Participant, Care provider, Investigator
Enrolment
24 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT06899334
Sponsor's protocol ID
BASEC 2024-01445
Acronym
LPD
Status last verified
Mar 2025
First submitted
14 Mar 2025
Last updated
27 Mar 2025
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing LSD, Psilocybin and DMT 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 7 inclusion and 13 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: looking for participants now, as of the sponsor's last update on 27 Mar 2025. 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?

This study is still under way. Results are not available in the source record yet.

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

Contact Matthias E Liechti, Prof. Dr. MD (61 328 68 68 ext. +41, matthias.liechti@usb.ch), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

1. Altered state of consciousness profile (5D-ASC) (time frame: 18 months). 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 NCT06899334.

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 27 Mar 2025; AzTrials last refreshed its copy on 8 Nov 2026.

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