QT Interval Prolongation with Ondansetron

Evidence of QT Prolongation

• The American Thoracic Society notes that ondansetron is a medication that can increase the risk of QT prolongation in patients, as stated in guidelines for non-tuberculous mycobacterial pulmonary disease management 1
• The American College of Cardiology guidelines state that antiemetics, including 5HT3 antagonists like ondansetron, can prolong the QT interval 2

Drug Interactions That Increase Risk

• The British Thoracic Society recommends avoiding concomitant use of ondansetron with other QT-prolonging medications, such as antiarrhythmics, antimalarials, antipsychotics, and certain antidepressants, to reduce the risk of QT prolongation and potential arrhythmias 1
• The European Society for Medical Oncology advises against combining ondansetron with antiviral drugs like lopinavir/ritonavir due to increased risk of QT prolongation 6
• The National Comprehensive Cancer Network suggests that antimalarials, such as chloroquine and hydroxychloroquine, should be used with caution in patients taking ondansetron due to the potential for QT prolongation 5

Monitoring Recommendations

• The American College of Cardiology recommends obtaining a baseline ECG in all patients and correcting electrolyte abnormalities prior to starting ondansetron treatment, with follow-up ECGs at appropriate intervals after initiation of therapy and following any dosing changes 2
• The American Society of Hematology suggests using alternative rate-correction formulas, such as Fridericia, Hodges, or Sagie/Framingham, instead of the Bazett formula when monitoring patients receiving arsenic trioxide and ondansetron 7

Management of QT Prolongation

• The American Heart Association recommends considering alternative antiemetics in patients with multiple risk factors for QT prolongation, as stated in clinical guidelines 3
• The European Respiratory Society advises that if QTc reaches >500 ms or increases >60 ms from baseline, ondansetron should be temporarily withheld, electrolyte abnormalities corrected, and other medications that may prolong QT interval discontinued if possible, with monitoring via ECG until QTc returns to acceptable range 7