pem pearl: iv ondansetron effect on qt interval
In this prospective, observational study of over 400 adults (average age 39, mostly healthy) the researchers monitored QT intervals at several time intervals both pre- and post-IV ondansetron administration. Notably, the vast majority of these patients got 8mg of Zofran, and only 12% received 4mg. Average prolongation was 8 milliseconds at 5 minutes and was nearly back to baseline by 30min.
Also notably, the prolongation was actually longer in the 4mg (average 10ms) group compared to the 8mg group (average 7ms).
While we need to be careful extrapolating adult data to kids, this group was a remarkably young group with very few comorbidities and not much use of other QT prolonging medications.
Bottom line: IV Ondansetron caused a rapid, brief and mild QT prolongation (average 8ms, peak effect at 5 min) in this large ADULT study.
Also notably, the prolongation was actually longer in the 4mg (average 10ms) group compared to the 8mg group (average 7ms).
While we need to be careful extrapolating adult data to kids, this group was a remarkably young group with very few comorbidities and not much use of other QT prolonging medications.
Bottom line: IV Ondansetron caused a rapid, brief and mild QT prolongation (average 8ms, peak effect at 5 min) in this large ADULT study.
