ONDANSETRON PLUS METOPIMAZINE COMPARED WITH ONDANSETRON ALONE IN PATIENTS RECEIVING MODERATELY EMETOGENIC CHEMOTHERAPY

Background and Methods. The serotonin (5-hydroxytryptamine3) antagonists have improved the treatment of acute chemotherapy-induced nausea and vomiting, but their ability to prevent delayed nausea and vomiting seems less pronounced. The results of a preliminary open trial suggested that the addition of a selective dopamine D2 antagonist could improve the antiemetic efficacy of the serotonin antagonists. In a randomized, double-blind, crossover trial, we compared oral treatment with ondansetron (8 mg twice a day) and the dopamine D2 antagonist metopimazine (30 mg four times a day) with treatment with ondansetron alone for three days in 30 patients who had vomited during the previous cycle of chemotherapy. All the patients received moderately emetogenic chemotherapy. Results, Combination treatment with ondansetron and metopimazine significantly reduced the incidence of acute (P = 0.006) and delayed (P = 0.02) nausea and acute (P = 0.02) and delayed (P = 0.006) vomiting, as compared with treatment with ondansetron alone. Patients had significantly fewer days of nausea (P = 0.03) and vomiting (P = 0.003) if they received combination therapy. Sixty-seven percent of the patients preferred ondansetron and metopimazine, and 33 percent favored ondansetron alone (P = 0.10). Adverse reactions were mild with both regimens. With the exception of constipation, which was reported more frequently with combination therapy (P = 0.03), there were no significant differences in adverse reactions. Conclusions. Ondansetron plus metopimazine is a highly effective and safe antiemetic regimen that is markedly superior to treatment with ondansetron alone in patients receiving moderately emetogenic chemotherapy.