Additive anti-emetic efficacy of prophylactic ondansetron with droperidol in out-patient gynecological laparoscopy.

Purpose: To determine the efficacy of ondansetron and droperidol, alone and in combination, administered for prophylaxis of postoperative nausea and vomiting (PONV) in women undergoing general anesthesia for outpatient gynecological laparoscopy.

Methods: Following Institutional Ethics Board approval and patient consent, 160 female out- patients scheduled for laparoscopy were randomly allotted in a double-blind fashion to receive: i) saline (placebo), ii) 4 mg ondansetron, iii) 1.25 mg droperidol, or iv) 4 mg ondansetron and 1.25 mg droperidol combination intravenously on induction. Following a standardized general anesthesia, patients were interviewed and assessed for PONV at various times.

Results: During the first 24 hr after surgery, the incidence of PONV in the placebo group was 71%. This was reduced to 61% with droperidol alone (P = 0.334), to 46% with ondansetron alone (P = 0.027), and to 23% with the combination group (P<0.001). A statistically significant difference was observed between combination and droperidol (P<0.001) and between combination and ondansetron (P = 0.036). There were fewer requests for rescue medication from the combination group (7.7%) than from the ondansetron and placebo groups.

Conclusion: The results of this study suggest that the combination of 4 mg ondansetron and 1.25 mg droperidol is more efficacious as a prophylactic anti-emetic than either agent alone during the 24 hr post-surgery. This additive effect may be due to the different mechanisms of action of ondansetron and droperidol.