Vilazodone for Cannabis Dependence: A Randomized, Controlled Pilot Trial

Background and Objectives: The purpose of this study was to evaluate the efficacy of vilazodone, a selective serotonin receptor inhibitor and partial 5-HT1A agonist, for treatment of cannabis dependence. Methods: Seventy-six cannabis-dependent adults were randomized to receive either up to 40 mg/day of vilazodone (n = 41) or placebo (n = 35) for 8 weeks combined with a brief motivational enhancement therapy intervention and contingency management to encourage study retention. Cannabis use outcomes were assessed via weekly urine cannabinoid tests; secondary outcomes included cannabis use self-report and cannabis craving. Results: Participants in both groups reported reduced self-reported cannabis use over the course of the study; however, vilazodone provided no advantage over placebo in reducing cannabis use. Men had significantly lower creatinine-adjusted cannabinoid levels and a trend for increased negative urine cannabinoid tests than women. Discussion and Conclusions: Vilazodone was not more efficacious than placebo in reducing cannabis use. Important gender differences were noted, with women having worse cannabis use outcomes than men. Scientific Significance: Further medication development efforts for cannabis use disorders are needed, and gender should be considered as an important variable in future trials.