OBJECTIVETo compare the efficacy of ondansetron and granisetron in the prevention of postoperative nausea and vomiting (PONV) in high-risk patients.

METHODSTotally 200 patients with three key risk factors for PONV (female, non-smoking and postoperative opioid use) were equally randomized into ondansetron group and granisetron group. Ondansetron (4 mg) or granisetron (3 mg) was intravenously administered upon the completion of surgery. The episodes of nausea and vomiting were observed for 24 hours after surgery.

RESULTSA significantly greater proportion of patients in granisetron group achieved a complete response (i.e., no PONV or rescue medication) during the first 24 hours postoperatively versus those in ondansetron group (62.6% vs. 46.9%, respectively; P=0.048). There were no significant differences in terms of postoperative nausea incidences (42.9% vs. 34.3%, respectively), postoperative vomiting incidences (25.5% vs. 20.2%, respectively) and postoperative rescue anti-emetics incidences (19.4% vs. 15.2%, respectively) (P>0.05).

CONCLUSIONGranisetron is more effective than ondansetron in preventing PONV in high-risk patients during the first 24 hours postoperatively.