Ondansetron suppository: a randomised, double-blind, double-dummy, parallel-group comparison with oral ondansetron for the prevention of cyclophosphamide-induced emesis and nausea. The Ondansetron Suppository emesis study group.

This multinational, multicentre, randomised, parallel-group study compared the safety, tolerability and efficacy of ondansetron 8 mg orally twice a day with ondansetron suppository 16 mg once daily in patients receiving cyclophosphamide-containing chemotherapy. A total of 406 patients were randomised to receive ondansetron 8 mg p.o. (198 patients) or ondansetron suppository (208 patients) medication in a double-blind, double-dummy trial. The primary efficacy analysis revealed that ondansetron provided good anti-emetic control with 81% of patients in the 8 mg p.o. b.d. group and 73% of patients in the 16 mg ondansetron suppository o.d. group experiencing complete or major control of emesis (< or = 2 emetic episodes) on the worst day of days 1-3. The 90% confidence interval for the difference between the two treatments for complete or major control (1.4, 15.0%) showed that the treatments could be regarded as equivalent. A difference in favour of oral ondansetron treatment was noted for the complete control (0 emetic episodes) rates over days 1-3, but no differences were found on day 1. There were no significant differences in the distribution of nausea grades between the treatment groups on the worst day of days 1-3 or on day 1. The incidence of adverse events was similar for the two treatment groups, the most frequently reported events were headache and constipation. There were no significant laboratory findings in either treatment group. In conclusion this study showed that the ondansetron treatments could be regarded as equivalent for the primary efficacy endpoint and that ondansetron suppository was well tolerated and effective in the prevention of cyclophosphamide-induced emesis.