Drug interactions
Dofetilide + Ondansetron
Severity: Major
Dofetilide and Ondansetron: major interaction.
Last updated Sources: UK SmPC
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Dofetilide markedly prolongs the QT interval, and ondansetron adds further prolongation. This raises the risk of torsades de pointes, which is especially hazardous because dofetilide has a narrow therapeutic window.
What this interaction means in plain words
Dofetilide and Ondansetron can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Dofetilide belongs to Cardiovascular; Ondansetron belongs to Gastrointestinal Tract.
Why it happens
Additive QT prolongation through blockade of the cardiac hERG potassium current.
What to do
Avoid ondansetron during dofetilide therapy where possible and choose a non-QT-prolonging antiemetic. If it cannot be avoided, monitor the ECG and keep potassium and magnesium normal.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Ondansetron
- Apomorphine + Ondansetron Contraindicated
- Ondansetron + Thioridazine Contraindicated
- Ondansetron + Vandetanib Contraindicated
- Adagrasib + Ondansetron Major
- Amiodarone + Ondansetron Major
- Amisulpride + Ondansetron Major
Other interactions of Dofetilide
- Amiodarone + Dofetilide Contraindicated
- Amisulpride + Dofetilide Contraindicated
- Amlodipine-hydrochlorothiazide-valsartan + Dofetilide Contraindicated
- Amlodipine-olmesartan-hydrochlorothiazide + Dofetilide Contraindicated
- Candesartan-hydrochlorothiazide + Dofetilide Contraindicated
- Captopril-hydrochlorothiazide + Dofetilide Contraindicated
Frequently asked questions
Can I take Dofetilide with Ondansetron?
MediHelp rates the interaction as major. Dofetilide and Ondansetron can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Dofetilide markedly prolongs the QT interval, and ondansetron adds further prolongation. This raises the risk of torsades de pointes, which is especially hazardous because dofetilide has a narrow therapeutic window.
How serious is the interaction between Dofetilide and Ondansetron?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid ondansetron during dofetilide therapy where possible and choose a non-QT-prolonging antiemetic. If it cannot be avoided, monitor the ECG and keep potassium and magnesium normal.
What other medicines interact with Ondansetron?
MediHelp also lists interactions of Ondansetron with, for example, Apomorphine, Thioridazine, Vandetanib. The full list is on the Ondansetron page.
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