Drug interactions
Disopyramide + Foscarnet
Severity: Major
Disopyramide 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
Disopyramide is a class Ia antiarrhythmic with a well-established risk of QT prolongation and torsade de pointes. Foscarnet can add to this through its own QT effect and by lowering serum calcium, magnesium and potassium. Together they may markedly increase the risk of life-threatening arrhythmia.
What this interaction means in plain words
Disopyramide 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.
Disopyramide belongs to Cardiovascular; Foscarnet belongs to Anti Virals.
Why it happens
Additive QT prolongation, with foscarnet-induced electrolyte depletion potentiating disopyramide proarrhythmia.
What to do
Avoid the combination where possible and choose an alternative antiarrhythmic or antiviral. If unavoidable, monitor ECG continuously or frequently and keep electrolytes within normal range.
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 Disopyramide
- Amisulpride + Disopyramide Contraindicated
- Desipramine + Disopyramide Contraindicated
- Disopyramide + Dronedarone Contraindicated
- Disopyramide + Itraconazole Contraindicated
- Disopyramide + Ketoconazole Contraindicated
- Disopyramide + Maprotiline Contraindicated
Frequently asked questions
Can I take Disopyramide with Foscarnet?
MediHelp rates the interaction as major. Disopyramide 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. Disopyramide is a class Ia antiarrhythmic with a well-established risk of QT prolongation and torsade de pointes. Foscarnet can add to this through its own QT effect and by lowering serum calcium, magnesium and potassium. Together they may markedly increase the risk of life-threatening arrhythmia.
How serious is the interaction between Disopyramide 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 where possible and choose an alternative antiarrhythmic or antiviral. If unavoidable, monitor ECG continuously or frequently and keep electrolytes within normal range.
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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