The Effect of Intravenous Ondansetron on QT Interval in the Emergency Department

The Effect of Intravenous Ondansetron on QT Interval in the Emergency Department

Authors: Huriye Yürük Mısırlıoğlu, Elif Öztürk İnce, Meltem Akkaş

Published in: American Journal of Emergency Medicine, August 2024

Conclusion: Intravenous administration of 4 mg and 8 mg ondansetron appears safe in the ED population, with QT prolongation remaining below clinically significant levels. Routine ECG monitoring may not be warranted in patients without known cardiac risks.

Methods: This prospective, observational cohort study included adult patients who received intravenous ondansetron in the ED over one year. Electrocardiograms (ECGs) were taken before and at 5, 15, and 30 minutes after ondansetron administration. The primary outcome was the degree of QT interval prolongation. The severity of QT prolongation was categorized based on the International Conference on Compliance (ICH) recommendations as 'negligible' (<5 ms), 'significant' (>20 ms), 'potential concern' (>30 ms), or 'definitely worrying' (>60 ms).

Results: The study included 435 patients, with a mean age of 39 years (±18), 60% of whom were female. The greatest QT prolongation occurred at 5 minutes post-administration (mean increase of 7.9 ± 18.1 ms) and remained consistent at 15 and 30 minutes. QT prolongation did not correlate with ondansetron dose, although QT measurements at 30 minutes were higher in patients who received 8 mg. No patients experienced cardiac arrhythmias during the study. The QT prolongation observed was considered above 'negligible' but below 'significant' according to ICH guidelines.

Discussion: The study found that while intravenous ondansetron caused a slight increase in QT interval, it did not reach levels considered clinically significant. No arrhythmias were observed, suggesting that routine ECG monitoring for QT prolongation in patients receiving ondansetron may not be necessary, particularly in the absence of underlying cardiac risks. This could help reduce unnecessary healthcare costs and improve patient flow in the ED.