Single dose intravenous ondansetron in the prevention of postoperative nausea and vomiting.

Postoperative nausea and vomiting continues to pose problems for surgical patients. Three studies were undertaken to evaluate the efficacy and safety of prophylactic intravenous ondansetron in male and female patients undergoing outpatient surgery. Studies 1 and 2 included a total of 1169 female patients scheduled to undergo surgery on a day case basis. In study 3, 468 male patients scheduled for outpatient surgery were enrolled. Patients received ondansetron or placebo prior to induction of anaesthesia. Efficacy and safety data were collected for 24 h postoperatively. Studies 1 and 2, individually, revealed that ondansetron 4 mg and 8 mg were significantly (p < or = 0.05) better than placebo at preventing emesis. A combined analysis showed that the 4 mg and 8 mg doses were significantly (p < or = 0.05) better than ondansetron 1 mg at preventing emesis, while 8 mg was not statistically different from 4 mg. Therefore, 4 mg was chosen as the optimal dose. In study 3, ondansetron 4 mg was significantly (p < or = 0.001) more effective than placebo in preventing emesis in males. There were no differences between treatment groups with respect to vital signs, laboratory values, or adverse events. Intravenous ondansetron is safe and effective at preventing postoperative nausea and vomiting in male and female patients undergoing day case surgery.