Antiemetic prophylaxis with promethazine or ondansetron in major gynaecological surgery

Abstract

Background: Postoperative nausea and vomiting remain a significant cause of morbidity among patients undergoing general anaesthesia. The optimal strategy for prevention, however, remains controversial. This study evaluated the efficacy of ondansetron 8 mg compared with promethazine 25 mg or placebo for the prevention of nausea and vomiting in patients undergoing elective major gynaecological surgery.

Methods: Seventy-five patients received intravenous injection of the study medication (ondansetron-25, promethazine-25 or placebo-25) immediately before the induction of anaesthesia. Nausea and vomiting were assessed over a 24-hour postoperative period.
Results: Nausea occurred in 20%, 40% and 72% of the promethazine, ondansetron and placebo groups respectively (p = 0.001). The overall incidence of vomiting was 12%, 16%, and 60% (p = 0.000) for promethazine, ondansetron and the placebo respectively. Postoperative drowsiness was prominent in the promethazine group. There was no significant difference in effectiveness between promethazine and ondansetron.

Conclusions: Promethazine 25 mg was significantly more effective than ondansetron 8 mg in the prevention of postoperative nausea and vomiting. Promethazine is inexpensive and the cost of drugs is of importance in developing African countries. Drowsiness was a significant side-effect with promethazine, and this will be a disadvantage in ambulatory surgery.