Efficacy of oral ondansetron in the prevention of emesis in outpatients receiving cyclophosphamide-based chemotherapy. The Ondansetron Study Group.

<bold>Objective: </bold>To evaluate the efficacy and safety of oral ondansetron (Zofran) as an antiemetic in patients receiving cyclophosphamide-based chemotherapy.<bold>Design: </bold>A multicenter, randomized, double-blind, stratified, placebo-controlled trial conducted between March 1989 and January 1990.<bold>Setting: </bold>Twenty-seven oncology centers including university hospitals, community cancer centers, and private medical oncology practices.<bold>Patients: </bold>A total of 349 chemotherapy-naive patients having their first cycle of cyclophosphamide (> or = 450 mg/m2)-based chemotherapy. Patients also received methotrexate (> or = 30 mg/m2) or doxorubicin (> or = 35 mg/m2). All patients were evaluated for safety and 318 (91%) were evaluated for efficacy.<bold>Interventions: </bold>Patients were randomly assigned to one of four treatment groups: placebo, 1 mg, 4 mg, or 8 mg of ondansetron. Assigned study medication was taken three times per day for 3 consecutive days.<bold>Measurements: </bold>Time and number of emetic episodes as well as degree of nausea were recorded by patients for each of the 3 study days.<bold>Results: </bold>Compared with placebo, all three doses of ondansetron were superior (P < 0.001) in preventing vomiting and controlling nausea. A complete response (no emetic episodes) was observed in 19%, 57%, 65%, and 66% of patients in the placebo, 1-mg, 4-mg, and 8-mg ondansetron groups, respectively. For patients who received higher-dose cyclophosphamide and doxorubicin, a dose-related trend in antiemetic efficacy of ondansetron was observed. Mild headache and constipation were the most frequently reported adverse events. No extrapyramidal reactions were observed.<bold>Conclusion: </bold>Oral ondansetron is a safe and effective antiemetic that is more efficacious than placebo for patients receiving cyclophosphamide-based chemotherapy. [ABSTRACT FROM AUTHOR]