Ondansetron ( Zofran ) is commonly used to treat vomiting in gastroenteritis, but has a United States FDA ( Food and Drug Administration ) black box warning for risk of Q wave to T wave time interval ( QT ) prolongation.
Two pediatric cases of fatal refractory cardiac arrest after administration of Ondansetron were reported.
A 10-year-old previously healthy boy presented to the emergency room with gastroenteritis symptoms. After intravenous fluids, morphine, antibiotics, and 2 doses of Ondansetron, the patient became unresponsive with agonal respirations and a wide complex tachycardia consistent with ventricular tachycardia.
In a second case, an 86-day-old infant with previously unidentified congenital cardiomyopathy presented to the Emergency department with gastroenteritis symptoms. The patient received Ondansetron and subsequently experienced repeated bouts of supraventricular tachycardia which progressed to ventricular fibrillation.
Resuscitation efforts failed in each case, and both patients expired.
Ondansetron can cause dose-dependent QT prolongation effects, which are more clinically relevant when other proarrhythmic elements are present.
There is very limited published experience on use of Ondansetron in children younger than 2 years.
These two cases join two previous case reports of death after Ondansetron administration for gastroenteritis.
In conclusion, patients may have hidden risk factors that, together with Ondansetron, could result in a proarrhythmic state that could lead to adverse effects, such as arrhythmias.
Administration of Ondansetron should be individualized and used cautiously in patients with risk factors for arrhythmia. ( Xagena )
Brenner SM, Boucher J, Pediatr Emerg Care 2016; 32: 779-784