THE EFFECT OF TIMING OF ONDANSETRON ADMINISTRATION ON ITS EFFICACY, COST-EFFECTIVENESS, AND COST-BENEFIT AS A PROPHYLACTIC ANTIEMETIC IN THE AMBULATORY SETTING

Although ondansetron (4 mg IV) is effective in the prevention and trea tment of postoperative nausea and vomiting (PONV) after ambulatory sur gery, the optimal timing of its administration, the cost-effectiveness , the cost-benefits, and the effect on the patient's quality of lift! after discharge have not been established. In this placebo-controlled double-blind study, 164 healthy women undergoing outpatient gynecologi cal laparoscopic procedures with a standardized anesthetic were random ized to receive placebo (Group A), ondansetron 2 mg at the start of an d 2 mg after surgery (Group B), ondansetron 4 mg before induction (Gro up C), or ondansetron 4 mg after surgery (Group D). The effects of the se regimens on :he incidence, severity, and costs associated with PONV and discharge characteristics were determined, along with the patient 's willingness to pay for antimetics. Compared with ondansetron given before induction of anesthesia, the administration of ondansetron afte r surgery was associated with lower nausea scores, earlier intake of n ormal food, decreased incidence of frequent emesis (more than two epis odes), and increased times until 25% of patients failed prophylactic a ntiemetic therapy (i.e., had an emetic episode or received rescue anti emetics for severe nausea) during the first 24 h postoperatively. This prophylactic regimen was also associated with the highest patient sat isfaction and lowest cost-effectiveness ratios. Compared with the plac ebo group, ondansetron administered after surgery significantly reduce d the incidence of PONV in the postanesthesia care unit and during the 24-h follow-up period and facilitated the recovery process by reducin g the time to oral intake, ambulation, discharge readiness, resuming r egular fluid intake and a normal diet. When ondansetron was given as a ''split dose,'' its prophylactic antiemetic efficacy was not signific antly different from that of the placebo group. Ln conclusion, the pro phylactic administration of ondansetron after surgery, rather than bef ore induction, may be associated with increased patient benefits. Impl ications: Ondansetron 4 mg IV administered immediately before the end of surgery was the most efficacious in preventing postoperative nausea and vomiting, facilitating both early and late recovery, and improvin g patient satisfaction after outpatient laparoscopy.