Double blind trial of delta-9-tetrahydrocannabinol (THC) versus placebo as an adjunct to prochlorperazine for chemotherapy-induced vomiting

Sixteen adult patients receiving outpatient cancer chemotherapy were enrolled in a trial of anti-emetic therapy. Serving as his or her own control, each individual received courses of prochlorperazine plus placebo randomly alternated with courses of prochlorperazine plus delta-9-tetrahydrocannabinol (THC). Vomiting occurred in 17 of 24 placebo courses and 16 of 28 THC courses (no significant difference, p = 31). However, 3 of the 16 patients vomited during the placebo courses but not during the THC courses. Two patients experienced dissociative reactions secondary to THC; there was no other adverse drug reaction. We conclude that prochlorperazine and THC can be given together safely, and that, in certain patients, the addition of THC to conventional anti-emetic therapy can be beneficial.