Delta-9-tetrahydrocannabinol as an antiemetic

The use of delta-9-tetrahydrocannabinol (THC) as an antiemetic in patients undergoing cancer chemotherapy is reviewed. The pharmacokinetics of THC is discussed, and the agent's effects on the central nervous, cardiovascular, respiratory, gastrointestinal, immune, endocrine, and reproductive systems are presented. The toxicology, potential hazards, and adverse reactions of THC are reviewed. Also reviewed are studies of THC's use as an antiemetic. THC appears to be an effective antiemetic in cancer patients undergoing chemotherapy. The maximal antinauseant effects often correlate with the attainment of a "high". THC has been found consistently more effective than placebo and at least as effective as prochlorperazine. In phenothiazine-resistant patients, THC's effectiveness has exceeded that of the phenothiazines. Efficacy may depend on the chemotherapeutic agent causing emesis. Elderly patients do not tolerate the THC "high" well. Concurrent administration of phenothiazines with THC may block the "high" without reducing THC's antiemetic effectiveness. Because of variations in individual tolerance, absorption, and the form of chemotherapy, flexibility is necessary in establishing the correct dose of THC.