Drug interactions
Fentanyl + Fosamprenavir
Severity: Major
Fentanyl and Fosamprenavir: 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
Fosamprenavir, via amprenavir, inhibits CYP3A4 and can increase fentanyl concentrations. This may cause serious or prolonged respiratory depression and sedation.
What this interaction means in plain words
Fentanyl and Fosamprenavir 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
Inhibition of CYP3A4 reduces fentanyl clearance.
What to do
Monitor frequently for respiratory depression and sedation and reduce the fentanyl dose as needed. Re-evaluate the dose when the protease inhibitor is stopped.
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
Frequently asked questions
Can I take Fentanyl with Fosamprenavir?
MediHelp rates the interaction as major. Fentanyl and Fosamprenavir 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. Fosamprenavir, via amprenavir, inhibits CYP3A4 and can increase fentanyl concentrations. This may cause serious or prolonged respiratory depression and sedation.
How serious is the interaction between Fentanyl and Fosamprenavir?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor frequently for respiratory depression and sedation and reduce the fentanyl dose as needed. Re-evaluate the dose when the protease inhibitor is stopped.
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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