[Evaluation of the administration time of ondansetron, a preventive for postoperative nausea and vomiting:...

To investigate the incidence of postoperative nausea and vomiting (PONV) depending on the administration time of ondansetron.

In this prospective, double-blind, parallel-group study we compared the prevention of PONV with ondansetron at two administration times versus placebo in 120 patients undergoing balanced general anaesthesia. The patients were stratified according to the type of surgery and randomly allocated to three treatment groups: 40 patients (Group A) received ondansetron 4 mg i.v. 10 min before the induction of anaesthesia and placebo 10 min before the end of surgery; 40 (Group B) received placebo 10 min before the induction of anaesthesia and ondansetron 4 mg i.v. 10 min before the end of surgery; and 40 (Group C) received placebo at both of the administrations. Data were analysed by Student's t-test and chi-square test; significance was taken at P < 0.05.

The analyses of the results showed a significantly lower incidence of PONV in treated patients (Groups A and B) than in the control group (Group C): postoperative nausea occurred in 12.5%, 27.5%, and 65% of patients in Groups A, B, and C, respectively, and was associated with vomiting in Group A in 2.5% Group B in 5%, and Group C in 55% of patients. Although the patients in Group A showed a lower incidence of PONV in comparison to those in Group B, the difference was not statistically significant.

The incidence of PONV was significantly lower in the groups with administration of 4 mg ondansetron. Ondansetron is therefore safe and affective in preventing PONV in surgical patients. The administration time does not influence the occurrence of PONV.