The Use of Ondansetron in the Treatment of Nausea and Vomiting Associated with Acetaminophen Poisoning

Abstract

Background: Nausea and vomiting associated with poisoning can complicate treatment and in some cases delay potential antidote administration. Side effects such as lowering the seizure threshold may at times discourage the use of traditionalphenothiazine and butyrophenone antiemetics. Methods: We performed a prospective, single arm, observational study examining the effectiveness of the 5HT₃ receptor antagonist ondansetron in the management of nausea and vomiting associated with acetaminophen poisoning. Patients with a history or laboratory evidence of acetaminophen poisoning were eligible for inclusion in the study. Exclusion criteria included age less than 18 or greater than 65, use of other antiemetic therapy within the previous 12 hours, history of preexisting hepatic or hematologic disease, pregnancy, or significant ingestion of other substances. Upon meeting entry criteria, patients were administered 8 mg of intravenous ondansetron. Nausea was graded on a 100 mm scale with number of emetic episodes recorded before and after treatment. Results: Six patients were entered in the study. All patients had nausea and at least one emetic episode prior to ondansetron and prior to administration of N-acetylcysteine. All patients reported relief of nausea after ondansetron. The degree of nausea decreased by an average of 52% at 30 min and 88% at 60 min following ondansetron administration. No significant vital sign changes were recorded in any patient, and there were no complications related to therapy. Three patients were administered N-acetylcysteine, and all tolerated this therapy without vomiting after ondansetron. Conclusions: Ondansetron appears to be a potentially useful adjunct in the management of nausea and vomiting associated with acetaminophen poisoning.