Drug interactions
Fentanyl transmucosal + Mifepristone
Severity: Major
Fentanyl transmucosal and Mifepristone: major 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
Fentanyl is a CYP3A4 substrate, and inhibition increases the swallowed and absorbed fraction's systemic exposure. This may lead to excessive sedation and respiratory depression.
What this interaction means in plain words
Fentanyl transmucosal and Mifepristone 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
Mifepristone inhibits CYP3A4, decreasing fentanyl clearance.
What to do
Avoid if possible or reduce the fentanyl dose and monitor sedation and respiratory rate frequently. Consider an alternative opioid less dependent on CYP3A4.
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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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 Fentanyl transmucosal with Mifepristone?
MediHelp rates the interaction as major. Fentanyl transmucosal and Mifepristone 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. Fentanyl is a CYP3A4 substrate, and inhibition increases the swallowed and absorbed fraction's systemic exposure. This may lead to excessive sedation and respiratory depression.
How serious is the interaction between Fentanyl transmucosal and Mifepristone?
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 or reduce the fentanyl dose and monitor sedation and respiratory rate frequently. Consider an alternative opioid less dependent on CYP3A4.
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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