Drug interactions
Mifepristone + Phenobarbital
Severity: Major
Mifepristone and Phenobarbital: 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
Phenobarbital is a well-known CYP3A4 inducer and is expected to reduce mifepristone exposure. Loss of effect may result, and the manufacturer advises against concurrent use with inducers.
What this interaction means in plain words
Mifepristone and Phenobarbital 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.
Why it happens
Phenobarbital induces CYP3A4, accelerating mifepristone metabolism.
What to do
Prefer an anticonvulsant that does not induce CYP3A4. If coadministration is unavoidable, monitor clinical and glycemic response and titrate mifepristone as needed.
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
Frequently asked questions
Can I take Mifepristone with Phenobarbital?
MediHelp rates the interaction as major. Mifepristone and Phenobarbital 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. Phenobarbital is a well-known CYP3A4 inducer and is expected to reduce mifepristone exposure. Loss of effect may result, and the manufacturer advises against concurrent use with inducers.
How serious is the interaction between Mifepristone and Phenobarbital?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Prefer an anticonvulsant that does not induce CYP3A4. If coadministration is unavoidable, monitor clinical and glycemic response and titrate mifepristone as needed.
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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