RANDOMIZED DOUBLE-BLIND, PLACEBO-CONTROLLED EVALUATION OF ORAL ONDANSETRON IN THE PREVENTION OF NAUSEA AND VOMITING ASSOCIATED WITH FRACTIONATED TOTAL-BODY IRRADIATION

Purpose: To evaluate oral ondansetron in the prevention of total-body irradiation (TBI)-induced nausea and vomiting. Methods: Twenty patients who received 4 days of TBI as part of their preparative regimen before bone marrow transplantation were randomized to receive either 8-mg oral doses of ondansetron or placebo. Administration of drug was double-blinded. Initial rescue therapy consisted of intravenous (IV) ondansetron 0.15 mg/kg following two or more emetic episodes between successive fractions of TBI or five total emetic episodes during the 4 days of therapy. If, after receipt of IV ondansetron, patients had two or more emetic episodes between fractions of TBI or five total emetic episodes, additional anti-emetics were administered. Results: Patients who received oral ondansetron had significantly fewer emetic episodes compared with those who received placebo (P = .005) over the entire 4-day study period. Oral ondansetron was also significantly superior to placebo with respect to the time of onset of emesis or rescue (P = .003). Six of 10 patients treated with oral ondansetron completed the study without additional antiemetic therapy, while none of 10 patients who received placebo completed the study without rescue antiemetic therapy. Six placebo patients who received initial rescue therapy with IV ondansetron required no additional antiemetics. No relationships were apparent between peak ondansetron concentration (Cmax) or area under the concentration versus time curve (AUC) and number of emetic episodes. Conclusion: Oral ondansetron is an effective therapy for the prevention of emesis induced by TBI.