Drug interactions
Dofetilide + Foscarnet
Severity: Major
Dofetilide and Foscarnet: major interaction.
Last updated Sources: US FDA label
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 has a narrow margin for QT prolongation and torsades de pointes, and its risk is strongly increased by low potassium or magnesium. Foscarnet can prolong QT and cause electrolyte depletion, so the combination may provoke a life-threatening arrhythmia.
What this interaction means in plain words
Dofetilide and Foscarnet 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; Foscarnet belongs to Anti Virals.
Why it happens
Additive QT prolongation compounded by foscarnet-induced electrolyte disturbances.
What to do
Avoid the combination if possible and use an alternative antiviral. If foscarnet is essential, monitor ECG continuously or frequently and maintain normal electrolytes.
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 Foscarnet
- Cidofovir + Foscarnet Contraindicated
- Foscarnet + Pimozide Contraindicated
- Foscarnet + Thioridazine Contraindicated
- Foscarnet + Vandetanib Contraindicated
- Adagrasib + Foscarnet Major
- Adefovir + Foscarnet 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 Foscarnet?
MediHelp rates the interaction as major. Dofetilide and Foscarnet 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 has a narrow margin for QT prolongation and torsades de pointes, and its risk is strongly increased by low potassium or magnesium. Foscarnet can prolong QT and cause electrolyte depletion, so the combination may provoke a life-threatening arrhythmia.
How serious is the interaction between Dofetilide and Foscarnet?
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 the combination if possible and use an alternative antiviral. If foscarnet is essential, monitor ECG continuously or frequently and maintain normal electrolytes.
What other medicines interact with Foscarnet?
MediHelp also lists interactions of Foscarnet with, for example, Cidofovir, Pimozide, Thioridazine. The full list is on the Foscarnet page.
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