Ondansetron dose response curve in high-risk pediatric patients

Study Objective: To establish a dose-response relationship for ondansetron, and to evaluate any effects of oral premedication with metoclopramide in pediatric patients undergoing tonsillectomy and adenoidectomy and strabismus surgery. Design: Prospective, randomized, double blind study. Setting: University affiliated, 280-bed pediatric hospital. Patients: 320 ASA physical status I and II patients between the ages of 2 and 12 years undergoing tonsillectomy and adenoidectomy or strabismus surgery. Interventions: Patients were randomized to eight investigational groups. Patients in all eight groups underwent a standard anesthetic. Groups 1, 2, 3, and 4 received intravenous (IV) saline or IV ondansetron at doses of 0.05 mg/kg, 0.1 mg/kg and 0.15 mg/kg, respectively. Groups 5, 6, 7, and 8 received oral metoclopramide 0.15 mg/kg as well as IV saline, and ondansetron 0.05 mg/kg, 0.1 mg/kg, or 0.15 mg/kg. Patients were evaluated for emetic episodes prior to and following discharge. Measurements and Main Results: All doses of ondansetron 0.05 mg/kg; 0.1 mg/kg; and 0.15 mg/kg were significantly more effective than placebo in reducing the incidence of emesis prior to, following discharge, and during the first 24 postoperative hours (p < 0.001). There were no significant differences in the occurrence of emesis between the groups receiving ondansetron 0.05 mg/kg, 0.1 mg/kg, and 0.15 mg/kg. The addition of oral metoclopramide 0.15 mg/kg had no effect on the incidence of emesis in the ondansetron or placebo study groups. Conclusions: Ondansetron is an effective medication for the treatment and prevention of postoperative nausea and vomiting, and a dose of ondansetron 0.05 mg/kg is as effective as 0.1 mg/kg and 0.15 mg/kg. Metoclopramide 0.15 mg/kg has no effect on the incidence of postoperative nausea and vomiting.