Synthetic Marijuana Effective in Delayed Chemotherapy-Induced Nausea and Vomiting

Paula Moyer, MA

May 24, 2005

May 24, 2005 (Orlando ) — The synthetic tetrahydrocannabinol dronabinol (Marinol) is effective in the treatment of delayed and acute chemotherapy-induced nausea and vomiting, according to investigators whose findings were presented here at the American Society of Clinical Oncology 2005 Annual Meeting.

"We found that dronabinol was as effective for delayed nausea and vomiting as aprepitant (Emend), which is more expensive," said principal investigator Eyal Meiri, MD, in an interview. "This finding may broaden options for patients who cannot afford standard therapy." Dr. Meiri is a staff oncologist at Bethesda Memorial Hospital in Boynton Beach, Florida.

Dronabinol currently is approved for the treatment of nausea and vomiting in patients who are unresponsive to other medications, and the investigators wanted to see if prophylactic use would provide relief regardless of patients' responses to other antiemetics.

Therefore, they recruited 64 cancer patients who were receiving moderate to high emetogenic chemotherapy and randomized them to a double-blind, placebo-controlled, flexible-dose trial. All subjects received 20 mg of dexamethasone orally and 16 mg of ondansetron intravenously before undergoing chemotherapy. In addition, the patients were divided into four groups: those who received only dronabinol, those who received only ondansetron, those who received a combination of dronabinol and ondansetron, and those who received placebo. Patients received 2.5 mg of dronabinol before and after treatment and 8 to 16 mg of odansetron.

Treatment continued through day 5 of the chemotherapy cycle, and patients' symptoms were assessed daily. The primary outcome measured was total response, which was defined as an intensity for the nausea that was less than 5 mm on a visual analog scale (VAS) and would be characterized by no vomiting or retching and no need to take a rescue antiemetic. The investigators also wanted to know how frequently nausea occurred, its intensity, and the number of vomiting or retching episodes. They compared the active treatments with each other and with placebo.

Overall, 61 patients were evaluable. All of the active treatments were statistically better than placebo; total response was observed in 54% (7/13) of dronabinol patients; 58% of the odansetron patients, 47% of the combination patients, and 20% of the placebo patients ( P < .05). Complete absence of nausea was observed in 71% of the dronabinol patients, 64% of the odansetron patients, 53% of the combination group, and 15% of those taking placebo. All active treatments were statistically better than placebo with respect to absence of nausea and nausea intensity. The average nausea intensity on the VAS was 10.1 mm for the dronabinol group, 24.0 mm in the odansetron group, 14.3 mm in the combination group, and 48.4 mm in the placebo group. The dronabinol patients had an average of 0.2 vomiting or retching episodes during the study period; the odansetron group had an average of 1.3 such episodes, as did the placebo group; the combination group had an average of 0.7 such episodes.

The investigators are planning to validate these findings with a larger clinical trial.

"The medical use of marijuana and the use of dronabinol in cancer-induced nausea and vomiting have been of active interest for a number of years," said Len Lichtenfeld, MD, in an interview seeking outside comment. "Although this was not a definitive study, the findings show that it should be explored further in this setting." Dr. Lichtenfeld is the deputy chief medical officer for the American Cancer Society in Atlanta, Georgia.

The study was funded by Solvay.

ASCO 2005 Annual Meeting: Abstract 8018. Presented May 15, 2005.

Reviewed by Gary D. Vogin, MD

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