Postoperative nausea and vomiting (PONV) are among the most common complications in surgical patients. In this prospective, double blind, parallel group study we compare the prophylactic antiemetic ...efficacy of ondansetron versus placebo in 90 patients undergoing general balanced anaesthesia. The patients were stratified according to the kind of surgery and randomly allocated to three treatment groups: 30 patients (Group A) received ondansetron 4 mg i.v. 1 hour before the induction of anaesthesia and placebo 1 hour before the end of surgery; 30 patients (Group B) received placebo 1 hour before the end of anaesthesia and ondansetron 4 mg i.v. 1 hour before the end of surgery; 30 patients (Group C-control group) received placebo in both the administrations. Data were analyzed by Student t test and chi 2 test; significance was taken at p < 0.05. The three groups proved comparable with respect to demographic characteristics, duration of anaesthesia and fentanyl consumption. Analysis of the results showed that PONV had a significantly lower incidence in treated patients (Groups A and B) than in the control group patients (Group C): postoperative nausea occurred in 13%, 30% and 67% of patients in Group A, B and C respectively and it was associated with vomiting in 3%, 7% and 57% of patients in Group A, B and C respectively. Although the patients in Group A showed a lower incidence of PONV in comparison to the patients in Group B, such differences proved to be not statistically significant. No adverse effects in relation to drug administration were observed. We conclude that ondansetron 4 mg i.v. is safe and effective in preventing PONV in the surgical patients, particularly when administered before the induction of anaesthesia.
