This randomised, placebo-controlled, triple-blind Phase I crossover trial (n=24) will compare the acute and subacute effects of LSD (150µg), psilocybin (30mg), and DMT (up to 2 mg/min intravenous infusion) in healthy adults, with all sessions standardised using ketanserin (20 mg IV) to end the psychedelic experience after three hours.
The LPD study is a 4-period randomized crossover in healthy volunteers to compare moderately high doses of LSD (150 µg), psilocybin (30 mg) and an IV DMT infusion (modeled to match oral kinetics) while standardising experience duration using 20 mg IV ketanserin at three hours.
Primary aims are basic science: to assess whether equivalent peak subjective effects occur across compounds when duration is fixed; outcomes include acute and subacute subjective measures and pharmacokinetic/pharmacodynamic characterisation.
150 µg oral LSD followed by 20 mg IV ketanserin at 3 h; part of 4-period randomized crossover.
150 µg oral LSD
Ketanserin 20 mg IV administered at 3 h to terminate experience
30 mg oral psilocybin followed by 20 mg IV ketanserin at 3 h; part of 4-period randomized crossover.
30 mg oral psilocybin
Ketanserin 20 mg IV administered at 3 h to terminate experience
Dose-escalating IV DMT infusion (modeled to match oral LSD/psilocybin time-course) up to 2 mg/min, followed by 20 mg IV ketanserin at 3 h; part of 4-period randomized crossover.
Dose-escalating IV infusion up to 2 mg/min to mimic oral time-course
Ketanserin 20 mg IV administered at 3 h to terminate experience
Oral and IV placebo followed by 20 mg IV ketanserin at 3 h; part of 4-period randomized crossover.
Oral and IV placebo as control
Ketanserin 20 mg IV administered at 3 h in placebo condition as per protocol