A systematic review of psilocybin-assisted therapy for substance use disorders identified four clinical trials (six articles) involving 151 patients, with doses from 6 to 40 mg. Three studies focused on alcohol use disorder and one on tobacco use disorder. In a pilot study (n=10), heavy drinking days decreased significantly. In another single-arm study (n=31), 32% achieved complete alcohol abstinence over an average of 6 years. A double-blind, placebo-controlled RCT (n=95) found significantly fewer heavy drinking days with psilocybin versus placebo. In a pilot study (n=15), smoking abstinence at 26 weeks was 80% and at 52 weeks 67%. All trials indicated beneficial effects, but larger RCTs are needed.
A single dose of ibogaine (10 mg/kg) in 14 patients with opioid use disorder caused an average QTc prolongation of 95 ms (range 29–146 ms); half of the subjects reached a QTc over 500 ms. No life-threatening cardiac events occurred, but severe temporary ataxia (inability to walk without support) was universal. Withdrawal and psychomimetic effects were mostly manageable; 11 of 14 patients did not return to morphine within 24 hours. The findings indicate that ibogaine induces clinically relevant but reversible QTc prolongation, bradycardia, and severe cerebellar toxicity.