Drug interactions
Fentanyl + Mifepristone
Severity: Major
Fentanyl 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
Mifepristone inhibits CYP3A4, which may raise fentanyl concentrations and prolong or intensify its effects. This can lead to sedation and respiratory depression, particularly with chronic mifepristone dosing as used in Cushing's syndrome.
What this interaction means in plain words
Fentanyl 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 belongs to Musculoskeletal; Mifepristone belongs to Endocrine.
Why it happens
Inhibition of CYP3A4-mediated metabolism of fentanyl.
What to do
Use the lowest effective fentanyl dose and monitor frequently for respiratory depression and sedation. Consider an alternative analgesic not dependent on CYP3A4 if long-term combined use is required.
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 Fentanyl
- Alvimopan + Fentanyl Contraindicated
- Fentanyl + Isocarboxazid Contraindicated
- Fentanyl + Olanzapine / samidorphan Contraindicated
- Fentanyl + Phenelzine Contraindicated
- Fentanyl + Tranylcypromine Contraindicated
- Alfentanil + Fentanyl Major
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 with Mifepristone?
MediHelp rates the interaction as major. Fentanyl 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. Mifepristone inhibits CYP3A4, which may raise fentanyl concentrations and prolong or intensify its effects. This can lead to sedation and respiratory depression, particularly with chronic mifepristone dosing as used in Cushing's syndrome.
How serious is the interaction between Fentanyl 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: Use the lowest effective fentanyl dose and monitor frequently for respiratory depression and sedation. Consider an alternative analgesic not dependent on CYP3A4 if long-term combined use is required.
What other medicines interact with Fentanyl?
MediHelp also lists interactions of Fentanyl with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Fentanyl page.
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