Despite significant advances in the delivery of general anaesthesia, postoperative nausea and vomiting (PONV) continue to be "the big 'little problem' for surgical patients", as described in a recent editorial [I]. Certain patient-related factors (gender, obesity, or history of motion sickness), surgical procedures (laparoscopy, strabismus surgery, or middle ear surgery), and anaesthetic techniques (nitrous oxide, narcotics, or inhalational agents) may affect the incidence of PONV [2]. As more and more surgery is being performed on a day case basis, the need for effective antiemetics, with fewer side effects than those currently in use, is becoming more urgent. Prophylactic antiemetic therapy in patient populations at high risk for PONV may not only be beneficial but also cost-effective if unanticipated hospital admissions for P O W can be avoided.Ondansetron, a 5-hydroxytryptamine subtype 3 (5-HT,) receptor antagonist, is an effective antiemetic in the prevention of chemotherapy-induced emesis [3]. Ondansetron has also been shown to be effective in the prevention [4] and treatment [5] of PONV. The results of three large multicentre, randomised, double-blind, placebo-controlled trials, examining the safety and efficacy of single dose intravenous prophylactic ondansetron in male and female patients, are presented here.
MethodWritten informed consent was obtained from all patients after approval of the protocols by the Institutional Review Board at each centre. In study 1, 580 ASA grade 1 or 2 female patients, aged 18-70 years, scheduled to undergo gynaecological laparoscopy on a day case basis, were enrolled. Five hundred and eighty-nine female patients, aged 18-70 years, scheduled to undergo day case surgery, were enrolled in study 2. In study 3,468 ASA grade 1 or 2 male patients, over 12 years of age, scheduled to undergo surgery on a day case basis, were enrolled. Patients who had vomited or received antiemetics within 24 h of surgery, were pregnant or breastfeeding (studies 1 and 2), were scheduled to undergo liver biopsy, required continuous gastric suction intraoperatively, or were greater than 100% over ideal body weight were not studied.Patients in all three studies were stratified into two groups: patients with a history of PONV after general anaesthesia, and patients with no history of PONV or no