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.