The effect of timing of ondansetron administration on its efficacy, cost-effectiveness, and cost-benefit as a prophylactic antiemetic in the ambulatory setting.

UNLABELLED Although ondansetron (4 mg I.V.) is effective in the prevention and treatment of postoperative nausea and vomiting (PONV) after ambulatory surgery, the optimal timing of its administration, the cost-effectiveness, the cost-benefits, and the effect on the patient's quality of life after discharge have not been established. In this placebo-controlled, double-blind study, 164 healthy women undergoing outpatient gynecological laparoscopic procedures with a standardized anesthetic were randomized to receive placebo (Group A), ondansetron 2 mg at the start of and 2 mg after surgery (Group B), ondansetron 4 mg before induction (Group C), or ondansetron 4 mg after surgery (Group D). The effects of these regimens on the incidence, severity, and costs associated with PONV and discharge characteristics were determined, along with the patient's willingness to pay for antiemetics. Compared with ondansetron given before induction of anesthesia, the administration of ondansetron after surgery was associated with lower nausea scores, earlier intake of normal food, decreased incidence of frequent emesis (more than two episodes), and increased times until 25% of patients failed prophylactic antiemetic therapy (i.e., had an emetic episode or received rescue antiemetics for severe nausea) during the first 24 h postoperatively. This prophylactic regimen was also associated with the highest patient satisfaction and lowest cost-effectiveness ratios. Compared with the placebo group, ondansetron administered after surgery significantly reduced the incidence of PONV in the postanesthesia care unit and during the 24-h follow-up period and facilitated the recovery process by reducing the time to oral intake, ambulation, discharge readiness, resuming regular fluid intake and a normal diet. When ondansetron was given as a "split dose," its prophylactic antiemetic efficacy was not significantly different from that of the placebo group. In conclusion, the prophylactic administration of ondansetron after surgery, rather than before induction, may be associated with increased patient benefits. IMPLICATIONS Ondansetron 4 mg I.V. administered immediately before the end of surgery was the most efficacious in preventing postoperative nausea and vomiting, facilitating both early and late recovery, and improving patient satisfaction after outpatient laparoscopy.