This non-treatment, randomised, triple-blind pharmacology study (n=20) used oral capsules of placebo or varying doses of dextromethorphan and psilocybin to study effects on mood and performance in healthy volunteers.
Twenty healthy volunteers (21–50 years) participate in multiple sessions including screening, preparation, five experimental drug sessions, immediate follow-ups, a 1-month follow-up and a post-completion urine collection; on each of five experimental sessions participants ingest capsules containing placebo or varying doses of one of multiple psychoactive compounds.
Subjective drug effects are measured using laboratory methods previously used by the group; tasks and questionnaires are completed acutely and at follow-up to characterise mood, cognition and drug-specific subjective effects.
Male participants receive oral capsules containing one of multiple psychoactive compounds or placebo across experimental sessions; compared with female arm.
Capsules contain placebo or varying doses of one of ~18 psychoactive compounds (hallucinogens, sedatives, stimulants, opioids, antihistamines, alcohol, nicotine, etc.).
Capsules contain placebo or varying doses of one of ~18 psychoactive compounds (hallucinogens, sedatives, stimulants, opioids, antihistamines, alcohol, nicotine, etc.).
Female participants receive oral capsules containing one of multiple psychoactive compounds or placebo across experimental sessions; compared with male arm.
Dextromethorphan
This double-blind experimental study (n=20) compares the effects of high-dose dextromethorphan (DXM; 400mg/70kg) to psilocybin (10, 20, 30mg/70kg) under conditions typical of therapeutic psychedelic trials. DXM and psilocybin showed increases over placebo in ratings of experiences predictive of psychological benefit at 1 week. However, psilocybin's effects were dose-dependent and more favourable, while DXM had poorer physical tolerability.