Drug interactions
Fosamprenavir + Tacrolimus
Severity: Major
Fosamprenavir and Tacrolimus: 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
Amprenavir, the active metabolite of fosamprenavir, inhibits CYP3A4 and can substantially raise tacrolimus concentrations, causing toxicity such as renal injury and neurotoxicity.
What this interaction means in plain words
Fosamprenavir and Tacrolimus 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
Amprenavir inhibits CYP3A4 metabolism of tacrolimus.
What to do
Reduce the tacrolimus dose and extend the dosing interval, with frequent trough monitoring and renal function checks.
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 Tacrolimus
- Adenovirus types 4 and 7 live + Tacrolimus Contraindicated
- Bcg vaccine live + Tacrolimus Contraindicated
- Cidofovir + Tacrolimus Contraindicated
- Cyclosporin + Tacrolimus Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Tacrolimus Contraindicated
- Measles mumps and rubella vaccine live + Tacrolimus Contraindicated
Frequently asked questions
Can I take Fosamprenavir with Tacrolimus?
MediHelp rates the interaction as major. Fosamprenavir and Tacrolimus 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. Amprenavir, the active metabolite of fosamprenavir, inhibits CYP3A4 and can substantially raise tacrolimus concentrations, causing toxicity such as renal injury and neurotoxicity.
How serious is the interaction between Fosamprenavir and Tacrolimus?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Reduce the tacrolimus dose and extend the dosing interval, with frequent trough monitoring and renal function checks.
What other medicines interact with Tacrolimus?
MediHelp also lists interactions of Tacrolimus with, for example, Adenovirus types 4 and 7 live, Bcg vaccine live, Cidofovir. The full list is on the Tacrolimus page.
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