BackgroundPostoperative nausea and vomiting following outpatient surgery can significantly delay discharge. This study evaluates the safety and efficacy of ondansetron (a new 5-HT, antagonist) in the treatment of postoperative nausea and vomiting in patients following outpatient surgery.MethodsFive hundred outpatient surgical patients (53 male and 447 female), receiving general endotracheal anesthesia, were studied at ten centers. Patients were stratified by gender and received, in a randomized, double-blind manner, 1, 4, or 8 mg ondansetron or placebo in response to nausea and/or vomiting postoperatively. Episodes of vomiting, nausea scores, adverse events, vital signs, and laboratory values were evaluated before and during the 24 h after study drug administration.ResultsComplete response to study medication (no vomiting and/or retching, and no rescue antiemetic over the initial 0–2-h period) was more frequent in the ondansetron groups (1 mg 57%, 4 mg 61%, and 8 mg 57%) than in the placebo group (30%, P <.001). For the 0–24-h study a complete response occurred in only 15% of the placebo group compared to 41%, 47%, and 47% of the 1-, 4-, and 8-mg ondansetron groups, respectively (P <.001 for all comparisons with placebo). Median nausea scores (range 0–10) during the initial observation period (0–2 h) were significantly lower for all doses of ondansetron (1.3, 0.8, 1.8 for 1, 4, and 8 mg, respectively) as compared with placebo (2.3). No significant differences occurred in hemodynamic stability, incidence of adverse events, or changes in laboratory values in the ondansetron groups compared to the placebo group.ConclusionsOndansetron, in doses less than 8 mg, is a safe, effective antiemetic for treating postoperative nausea and vomiting.