Antiemetic effect of intramuscular levonantradol in patients receiving anticancer chemotherapy.

Positive results of investigations of the antiemetic activity of delta-9-tetrahydrocannabinol (THC) in patients receiving cancer chemotherapy have led to the development of levonantradol, a synthetic derivative of THC. We assessed both the antiemetic activity and toxicity of intramuscular levonantradol in patients receiving cancer chemotherapy who were refractory to conventional antiemetic therapy. An open dose-finding study was conducted using initial doses of 0.5 mg. Doses were escalated by 0.5 mg when an incomplete response with no toxicity was observed. Of the 28 patients initially treated, 25/28 (89 per cent) achieved a complete or partial antiemetic response at doses ranging from 0.5 to 1.5 mg. There was no difference in response rate with respect to age or patient size. Of the 31 patients evaluable for toxicity, six reported none. Dysphoria, the dose-limiting toxicity, occurred in five patients (16 per cent) at 1.0 to 1.5-mg doses. The most commonly reported side effects were somnolence (48 per cent) and dry mouth (32 per cent). We conclude that intramuscular levonantradol is an effective antiemetic at doses as low as 0.5 mg.