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The following is a summary of “Effect of intravenous ondansetron on QT interval in the emergency department,” published in the August 2024  issue of Emergency Medicine by Mısırlıoğlu et al.

Ondansetron, a 5HT3 receptor antagonist used for treating nausea and vomiting, which had a warning issued in 2011 by the Food and Drug Administration (FDA), may cause QT prolongation, potentially leading to deadly arrhythmias. 

Researchers conducted a retrospective study to characterize the QT interval prolongation associated with ondansetron use in the Emergency Department (ED).

They evaluated patients in the ED for 1 year and were treated with intravenous ondansetron. QT prolongation associated with dosages was investigated. ECGs were obtained before the medication and 5, 15, and 30 minutes after IV drug administration. Every QT measurement was recorded and compared to the zero point. The severity of drug-induced QT prolongation was determined according to the recommendations of the International Conference on Compliance (ICH). QTc prolongation was categorized as ‘negligible’ (<5 ms), significant (>20 ms), potential concern (>30 ms), or worrying (>60 ms).

The results showed from 435 patients, 60% (261) were female, and the mean age was 39 (±18). The QT prolongation had a peak at the 5th minute and remained constant at the 15th and 31st minute. The maximum prolongation of the mean QT duration was at the 5th minute (7.9 ± 18.1 ms). No patient had any problems with cardiac conduction. The prolonged QT interval was not related to the dose of ondansetron, but QT measurements were higher in the 30th minute in patients treated with 8 mg of ondansetron. According to the ICH recommendations, the effect of ondansetron administration on QT prolongation was found to be above the negligible but below the significant value.

They concluded that routine ECG monitoring for ondansetron-induced QTc prolongation in emergency patients is not cost-effective, as IV administration of 4 mg and 8 mg doses did not pose a significant risk of QT prolongation.

Source: sciencedirect.com/science/article/abs/pii/S073567572400398X#preview-section-abstract