Double-blind, randomised, 2-period crossover in healthy adults (n=24) testing whether ketanserin 40 mg given 1 hour after 100 µg LSD shortens and attenuates acute subjective LSD effects.
This double-blind, random-order, two-period crossover study in healthy volunteers compares 100 µg LSD followed by ketanserin 40 mg versus 100 µg LSD followed by placebo to assess whether post-hoc 5-HT2A antagonism shortens and reduces psychedelic effects.
Primary purpose is basic science: to probe competitive antagonism at the 5-HT2A receptor and characterise acute subjective and physiological effects. Outcomes include subjective ratings, safety measures and pharmacodynamic observations.
100 µg LSD with ketanserin placebo (mannitol)
Single 100 µg LSD dose
Ketanserin placebo (mannitol)
100 µg LSD with oral ketanserin 40 mg
Single 100 µg LSD dose
Ketanserin 40 mg administered 1 hour after LSD