Prophylactic oral dolasetron mesylate reduces nausea and vomiting after abdominal hysterectomy. The Canadian Dolasetron Study Group

PURPOSE: The incidence of postoperative nausea and vomiting (PONV) varies from 50% to 75% after gynaecological surgery under general anaesthesia. This study evaluates the dose-response relationships, safety, and efficacy of the new 5-HT3 antagonist, dolasetron mesylate, in the prevention of PONV in women undergoing total abdominal hysterectomy (TAH). METHODS: Three hundred and seventy four women scheduled for TAH under general anaesthesia were studied at 13 Canadian centres. Patients received in a randomized, double-blind manner 25, 50, 100, or 200 mg dolasetron or placebo po one to two hours before induction of anaesthesia. The anesthetic protocol was standardized. Efficacy was evaluated for 24 hr after surgery by comparing the number of emetic episodes, administration of rescue medication, severity of nausea, and patient satisfaction. RESULTS: Analysis of complete response (no emetic episodes and no rescue for 24 hr) revealed a linear dose-response relationship across dolasetron groups (P < 0.002). Dolasetron 100 mg (P < 0.003) and 200 mg (P < 0.01) were superior to placebo. The percentage of patients with no emetic episodes increased from 29.3% (placebo) to 54.1 % (100 mg). Subgroup analysis revealed ASA status (I > II), previous history of PONV, previous history of motion sickness, and total morphine dose (> 55 mg associated with less PONV than < 55 mg) influenced the incidence of emetic symptoms, but did not alter the results of the primary analysis. CONCLUSION: Prophylactic dolasetron (100 mg and 200 mg) reduces the incidence of PONV in patients having total abdominal hysterectomy.