A Phase 1 interventional study of LSD and Psilocybin in Healthy, sponsored by University Hospital, Basel, Switzerland. Recruiting at 1 site in Switzerland. Open to participants aged 25 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-03-27.
Sponsored by University Hospital, Basel, Switzerland · Phase 1, Interventional, and Basic science
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.
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.
University Hospital, Basel, Switzerland is the lead sponsor of 968 studies on the registry; 191 are open to participants now.
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Exclusion Criteria:
150 µg lysergic acid diethylamide followed by 20 mg ketanserin intravenously after 3 h
Drug: LSD
30 mg Psilocybin followed by 20 mg ketanserin intravenously after 3 h
Drug: Psilocybin
Dose escalating DMT intravenous infusion up to 2 mg/min followed by 20 mg ketanserin intravenously after 3 h
Drug: DMT
Placebo followed by 20 mg ketanserin intravenously after 3 h
Drug: Placebo
A moderate to high oral dose of 150 µg LSD will be administered followed by 20 mg intravenous ketanserin after 3 h
A moderate to high oral dose of 30 mg psilocybin will be administered followed by 20 mg intravenous ketanserin after 3 h
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
An oral and an intravenous placebo will be administered followed by 20 mg intravenous ketanserin after 3 h
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.
Time frame: 18 months
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.
Time frame: 18 months
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.
Time frame: 18 months
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).
Time frame: 18 months
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.
Time frame: 18 months
Plasma levels of LSD
Assessed 20 times on each study day via blood samples
Time frame: 18 months
Plasma levels of psilocybin
Assessed 20 times on each study day via blood samples
Time frame: 18 months
Plasma levels of DMT
Assessed 20 times on each study day via blood samples
Time frame: 18 months
Plasma levels of ketanserin
Assessed 20 times on each study day via blood samples
Time frame: 18 months
Plasma levels of oxytocin
Assessed 2 times on each study day via blood samples
Time frame: 18 months
Plasma levels of prolactin
Assessed 2 times on each study day via blood samples
Time frame: 18 months
Plasma levels of cortisol
Assessed 2 times on each study day via blood samples
Time frame: 18 months
Autonomic effects I
Assessed 16 times on each study day via systolic and diastolic blood pressure
Time frame: 18 months
Autonomic effects II
Assessed 16 times on each study day via heart rate
Time frame: 18 months
Autonomic effects III
Assessed one time at screening visit and twice on each study day via ECG (QT-time)
Time frame: 18 months
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."
Time frame: 18 months
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."
Time frame: 18 months
Adverse Events (AE)
Any report of adverse events will be recorded on a AE-Form.
Time frame: 18 months
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University Hospital, Basel, Switzerland