Drug interactions
Mifepristone + Primidone
Severity: Major
Mifepristone and Primidone: 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
Primidone is metabolized to phenobarbital, which induces CYP3A4, so it can lower mifepristone exposure. This may reduce effectiveness, and inducers have not been studied with mifepristone.
What this interaction means in plain words
Mifepristone and Primidone 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; Primidone belongs to Central Nervous System.
Why it happens
Primidone and its metabolite phenobarbital induce CYP3A4, increasing mifepristone metabolism.
What to do
Avoid if possible by using a non-inducing anticonvulsant. If the combination is needed, monitor clinical response and adjust mifepristone dose.
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 Primidone
- Lorlatinib + Primidone Contraindicated
- Lurasidone + Primidone Contraindicated
- Primidone + Ranolazine Contraindicated
- Primidone + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Primidone + Voriconazole Contraindicated
- Abiraterone + Primidone Major
Frequently asked questions
Can I take Mifepristone with Primidone?
MediHelp rates the interaction as major. Mifepristone and Primidone 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. Primidone is metabolized to phenobarbital, which induces CYP3A4, so it can lower mifepristone exposure. This may reduce effectiveness, and inducers have not been studied with mifepristone.
How serious is the interaction between Mifepristone and Primidone?
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 if possible by using a non-inducing anticonvulsant. If the combination is needed, monitor clinical response and adjust mifepristone dose.
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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