Drug interactions
Mestranol + Mifepristone
Severity: Moderate
Mestranol and Mifepristone: moderate 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
Mestranol is a prodrug of ethinylestradiol, and mifepristone may raise estrogen exposure via CYP3A4 inhibition. With chronic mifepristone, unopposed estrogen effects on the endometrium are a concern because of its antiprogestogenic action.
What this interaction means in plain words
Mestranol and Mifepristone can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
CYP3A4 inhibition by mifepristone and progesterone receptor antagonism.
What to do
Use a non-hormonal contraceptive method during chronic mifepristone therapy. Monitor for abnormal uterine bleeding and estrogen adverse effects.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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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 Mestranol with Mifepristone?
MediHelp rates the interaction as moderate. Mestranol and Mifepristone can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Mestranol is a prodrug of ethinylestradiol, and mifepristone may raise estrogen exposure via CYP3A4 inhibition. With chronic mifepristone, unopposed estrogen effects on the endometrium are a concern because of its antiprogestogenic action.
How serious is the interaction between Mestranol and Mifepristone?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use a non-hormonal contraceptive method during chronic mifepristone therapy. Monitor for abnormal uterine bleeding and estrogen adverse effects.
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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