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.
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.
LSD 150 µg orally with ketanserin 40 mg orally administered after LSD.
Ketanserin 40 mg orally, single dose.
LSD 150 µg orally with olanzapine 10 mg orally administered after LSD.
Olanzapine 10 mg orally, single dose.
LSD 150 µg orally with lorazepam 2 mg orally administered after LSD.
Lorazepam 2 mg orally, single dose.
LSD 150 µg orally with matching placebo for post‑LSD medication.
Placebo (mannitol) capsule matching post‑LSD medication.
Placebo capsules for both administrations (no active LSD).
Placebo (mannitol) capsule.
Placebo (mannitol) capsule.