Drug interactions
Mifepristone + Ospemifene
Severity: Moderate
Mifepristone and Ospemifene: 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
Mifepristone inhibits CYP3A4 and may raise ospemifene concentrations, which are partly dependent on this enzyme. Increased exposure could amplify estrogen-agonist effects such as endometrial stimulation and thromboembolic risk.
What this interaction means in plain words
Mifepristone and Ospemifene 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.
Mifepristone belongs to Endocrine; Ospemifene belongs to Endocrine.
Why it happens
Mifepristone inhibits CYP3A4 and CYP2C9-mediated clearance of ospemifene is partly impaired, increasing exposure.
What to do
Monitor for ospemifene adverse effects such as vaginal bleeding and hot flashes. Consider an alternative if the patient is at high thromboembolic risk.
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
Other interactions of Ospemifene
- Bazedoxifene-conjugated estrogens + Ospemifene Contraindicated
- Estradiol + Ospemifene Contraindicated
- Clomiphene + Ospemifene Major
- Fluconazole + Ospemifene Major
- Ketoconazole + Ospemifene Major
- Ospemifene + Raloxifene Major
Frequently asked questions
Can I take Mifepristone with Ospemifene?
MediHelp rates the interaction as moderate. Mifepristone and Ospemifene 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. Mifepristone inhibits CYP3A4 and may raise ospemifene concentrations, which are partly dependent on this enzyme. Increased exposure could amplify estrogen-agonist effects such as endometrial stimulation and thromboembolic risk.
How serious is the interaction between Mifepristone and Ospemifene?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for ospemifene adverse effects such as vaginal bleeding and hot flashes. Consider an alternative if the patient is at high thromboembolic risk.
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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