THE DOSE-RESPONSE RELATIONSHIP OF ONDANSETRON IN PREVENTING POSTOPERATIVE EMESIS IN PEDIATRIC-PATIENTS UNDERGOING AMBULATORY SURGERY

Background: Postoperative nausea and vomiting is a distressing anesthetic complication that may delay discharge after ambulatory surgery. Effective prophylaxis for postoperative nausea and vomiting can be achieved in adults with lower doses of ondansetron, a 5-hydroxytryptamine subtype 3 receptor antagonist, compared with chemotherapy-induced emesis, However, the doses of ondansetron used in preventing postoperative nausea and vomiting in children are based on data from chemotherapy-induced emesis. The dose-related efficacy of intravenous ondansetron in the prophylaxis of postoperative emesis in the pediatric outpatient population was determined. Methods: In a double-blind, randomized placebo-controlled study, 130 patients (mean age 5.7 +/- 3.4 yr) received placebo, 10, 50, or 100 mu g/kg ondansetron during a standardized anesthetic. Episodes of postoperative vomiting or retching were recorded. Results: Intravenous ondansetron in a dose of 50 mu g/kg was more effective than placebo or a dose of 10 mu g/kg in controlling the incidence and frequency of emesis in the hospital and during the first 24 postoperative hours. Increasing the dose of ondansetron to 100 mu g/kg intravenously did not significantly reduce the incidence or frequency of emesis compared to 50 mu g/kg intravenously. Conclusions: Intravenous ondansetron in a dose of 50 mu g/ kg is as effective as larger doses for the prophylaxis of emesis in children undergoing surgical procedures known to be associated with an increased risk for postoperative nausea and vomiting.