Clinical TrialHealthy VolunteersLSDPlaceboLSDPlaceboLSDPlaceboLSDPlaceboPlaceboPlaceboCompleted

Effect of Ketanserin, Olanzapine, and Lorazepam After LSD Administration on the Acute Response to LSD in Healthy Subjects (LBL)

This randomised, double-blind, placebo-controlled crossover trial (n=20) conducted by the University Hospital in Basel, Switzerland, aims to investigate the effects of ketanserin, olanzapine, and lorazepam administered after LSD (150µg) on the acute response to LSD in healthy subjects.

Target Enrollment
20 participants
Study Type
Phase I interventional
Design
Randomized, quadruple Blind

Detailed Description

Randomised, quadruple‑blind crossover in healthy volunteers comparing single doses of LSD 150 µg with post‑LSD administration of ketanserin 40 mg, olanzapine 10 mg, lorazepam 2 mg, or placebo to assess attenuation and shortening of the acute LSD response.

The study examines pharmacological interventions as emergency or mitigation strategies for acute psychedelic distress and to probe the role of ongoing 5‑HT2A receptor stimulation in mediating subjective effects.

Outcomes include duration and intensity of subjective drug effects, changes in quality of experience, sensorimotor gating, sleep measures and safety/tolerability.

Study Arms & Interventions

LSD + ketanserin

experimental

LSD 150 µg orally with ketanserin 40 mg orally administered after LSD.

Interventions

  • LSD150 µg
    via Oral• single dose• 1 doses total
  • Placebo
    via Oral• single dose

    Ketanserin 40 mg orally, single dose.

LSD + olanzapine

experimental

LSD 150 µg orally with olanzapine 10 mg orally administered after LSD.

Interventions

  • LSD150 µg
    via Oral• single dose• 1 doses total
  • Placebo
    via Oral• single dose

    Olanzapine 10 mg orally, single dose.

LSD + lorazepam

experimental

LSD 150 µg orally with lorazepam 2 mg orally administered after LSD.

Interventions

  • LSD150 µg
    via Oral• single dose• 1 doses total
  • Placebo
    via Oral• single dose

    Lorazepam 2 mg orally, single dose.

LSD + placebo

active comparator

LSD 150 µg orally with matching placebo for post‑LSD medication.

Interventions

  • LSD150 µg
    via Oral• single dose• 1 doses total
  • Placebo
    via Oral• single dose

    Placebo (mannitol) capsule matching post‑LSD medication.

Placebo + placebo

inactive

Placebo capsules for both administrations (no active LSD).

Interventions

  • Placebo
    via Oral• single dose

    Placebo (mannitol) capsule.

  • Placebo
    via Oral• single dose

    Placebo (mannitol) capsule.

Participants

Ages
25 – 65
Sexes
Male & Female

Inclusion Criteria

  • Inclusion Criteria:\n\n1. Age between 25 and 65 years\n2. Sufficient understanding of the German language\n3. Understanding of procedures and risks associated with the study\n4. Willing to adhere to the protocol and signing of the consent form\n5. Willing to refrain from the consumption of illicit psychoactive substances during the study\n6. Abstaining from xanthine-based liquids and foods from the evenings prior to the study sessions to the end of the study days, limit coffee drinking ≤ 3 cups per day for 7 days prior to study day\n7. Participants must be willing not to drive a traffic vehicle or to operate machines within 48 h after substance administration\n8. Willing to use effective contraceptive measures throughout study participation (according to Clinical Trial Facilitation Group (CTFG): Recommendations related to contraception and pregnancy testing in clinical trials)\n9. Women of childbearing potential must have a negative pregnancy test at the beginning of the study. Pregnancy tests are repeated before each study session.\n10. Body mass index between 18 - 29 kg/m2

Exclusion Criteria

  • Exclusion Criteria:\n\n1. Chronic or acute medical condition\n2. Current or previous major psychiatric disorder including psychotic disorder, mania / hypomania, borderline personality disorders.\n3. Psychotic disorder or bipolar disorder in first-degree relatives\n4. Known hypersensitivity to LSD, ketanserin, olanzapine or lorazepam\n5. Hypertension (>140/90 mmHg) or hypotension (SBP < 85 mmHg)\n6. Hallucinogenic substance use (not including cannabis) more than 10 times or any time within the previous two months\n7. Pregnancy or current breastfeeding\n8. Participation in another clinical trial (currently or within the last 30 days)\n9. Use of medication that may interfere with the effects of the study medication\n10. Current substance use disorder (within the last 2 months)\n11. Tobacco smoking (>1 cigarette/day)\n12. Consumption of alcoholic beverages (>15 drinks/week)\n13. Not exhibiting consistent startle responding on the screening day (i.e., over 75% discernible responses to six 108 dB 40 ms startle pulses), as this would preclude the ability to measure fear potentiated startle.\n14. Use of strong CYP2D6 inhibitor\n15. Use of strong CYP1A2 inhibitor or inducer

Study Details

Locations

University Hospital Basel — Basel, Canton of Basel-City, Switzerland

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