Drug interactions
Mifepristone + Ritonavir
Severity: Major
Mifepristone and Ritonavir: 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
Ritonavir is a strong CYP3A4 inhibitor and raises mifepristone exposure, while mifepristone may raise ritonavir levels. Both can prolong the QT interval and mifepristone may cause hypokalemia, so arrhythmia risk is increased.
What this interaction means in plain words
Mifepristone and Ritonavir 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 belongs to Endocrine; Ritonavir belongs to Anti Virals.
Why it happens
Reciprocal CYP3A4 inhibition and additive QT prolongation.
What to do
Use an alternative if available. If combined, cap mifepristone at 300 mg/day for Cushing syndrome and monitor ECG and serum potassium.
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 Mifepristone
- Apixaban + Mifepristone Contraindicated
- Argatroban + Mifepristone Contraindicated
- Cisapride + Mifepristone Contraindicated
- Cortisone + Mifepristone Contraindicated
- Cyclosporin + Mifepristone Contraindicated
- Dabigatran etexilate + Mifepristone Contraindicated
Other interactions of Ritonavir
- Alfuzosin + Ritonavir Contraindicated
- Amiodarone + Ritonavir Contraindicated
- Avanafil + Ritonavir Contraindicated
- Colchicine + Ritonavir Contraindicated
- Dronedarone + Ritonavir Contraindicated
- Eletriptan + Ritonavir Contraindicated
Frequently asked questions
Can I take Mifepristone with Ritonavir?
MediHelp rates the interaction as major. Mifepristone and Ritonavir 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. Ritonavir is a strong CYP3A4 inhibitor and raises mifepristone exposure, while mifepristone may raise ritonavir levels. Both can prolong the QT interval and mifepristone may cause hypokalemia, so arrhythmia risk is increased.
How serious is the interaction between Mifepristone and Ritonavir?
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. If combined, cap mifepristone at 300 mg/day for Cushing syndrome and monitor ECG and serum potassium.
What other medicines interact with Mifepristone?
MediHelp also lists interactions of Mifepristone with, for example, Apixaban, Argatroban, Cisapride. The full list is on the Mifepristone page.
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