A SINGLE IV DOSE OF ONDANSETRON 8-MG PRIOR TO INDUCTION OF ANESTHESIAREDUCES POSTOPERATIVE NAUSEA AND VOMITING IN GYNECOLOGICAL PATIENTS

The effect of a single intravenous dose of ondansetron in preventing p ostoperative nausea and emesis (retching and vomiting) (PONV) was inve stigated in a randomized, double-blind, placebo-controlled multicentre , international study. Women of ASA class I-III, requiring gynaecologi cal laparotomy, vaginal hysterectomy, or major vaginal surgery were se lected for study Two hundred and thirty-five received placebo, 231 rec eived 1 mg ondansetron, 228 received 8 mg ondansetron and 229 received 16 mg ondansetron, as an infusion over five minutes before the induct ion of anaesthesia. A standardized balanced anaesthetic technique was employed. This consisted of premedication with either diazepam or tema zepam, thiopentone induction, maintenance with nitrous oxide in oxygen supplemented with enflurane or isoflurane, intraoperative analgesia w ith fentanyl, neuromuscular blockade with any choice of agent and reve rsal with neostigmine and atropine. Postoperative analgesia was achiev ed with morphine, and prochlorperazine or metoclopramide were given if a rescue antiemetic was required. A greater percentage of patients in the 8 mg and 16 mg ondansetron groups experienced no postoperative em esis (44% and 39% respectively) than in the placebo and 1 mg ondansetr on groups (29% and 28% respectively) for the first 24 hr postoperative period (8 mg vs placebo and 1 mg: P less-than-or-equal-to 0.001; 16 m g vs placebo: P < 0.05; 16 mg vs 1 mg: P < 0.05). Similarly, the perce ntage of patients who did not experience postoperative nausea were 20% , 26%, 31% and 28% for the placebo, 1 mg, 8 mg and 16 mg ondansetron t reatment groups, respectively (8 mg and 16 mg vs placebo P < 0.05). Ov erall, the incidences of adverse events in the ondansetron and placebo groups were similar. It is concluded that intravenous ondansetron, at doses of 8 mg and 16 mg, is both well tolerated and effective in prev enting postoperative nausea and emesis, and no greater benefit was obs erved with the 16 mg dose in comparison with the 8 mg dose.