Drug interactions
Foscarnet + Mifepristone
Severity: Major
Foscarnet and Mifepristone: major interaction.
Last updated
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
Mifepristone, particularly at the higher doses used for Cushing's syndrome, prolongs the QT interval, and foscarnet adds to this effect and to electrolyte depletion. Torsades de pointes risk is increased.
What this interaction means in plain words
Foscarnet and Mifepristone 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.
Foscarnet belongs to Anti Virals; Mifepristone belongs to Endocrine.
Why it happens
Additive QT prolongation with foscarnet-induced electrolyte disturbances.
What to do
Use an alternative if available; otherwise monitor ECG and keep potassium, magnesium and calcium 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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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 Mifepristone
- Apixaban + Mifepristone Contraindicated
- Argatroban + Mifepristone Contraindicated
- Cisapride + Mifepristone Contraindicated
- Cortisone + Mifepristone Contraindicated
- Cyclosporin + Mifepristone Contraindicated
- Dabigatran etexilate + Mifepristone Contraindicated
Frequently asked questions
Can I take Foscarnet with Mifepristone?
MediHelp rates the interaction as major. Foscarnet and Mifepristone 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. Mifepristone, particularly at the higher doses used for Cushing's syndrome, prolongs the QT interval, and foscarnet adds to this effect and to electrolyte depletion. Torsades de pointes risk is increased.
How serious is the interaction between Foscarnet and Mifepristone?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use an alternative if available; otherwise monitor ECG and keep potassium, magnesium and calcium normal.
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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