Drug interactions
Nirmatrelvir / ritonavir + Tacrolimus
Severity: Major
Nirmatrelvir / ritonavir and Tacrolimus: 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
The ritonavir-boosted nirmatrelvir combination strongly inhibits CYP3A and can raise tacrolimus exposure many-fold within days. This risks nephrotoxicity, neurotoxicity, hyperkalemia and QT prolongation. The effect persists for some days after the antiviral course ends.
What this interaction means in plain words
Nirmatrelvir / ritonavir 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
Ritonavir and nirmatrelvir inhibit CYP3A4 and P-glycoprotein, markedly decreasing tacrolimus metabolism and efflux.
What to do
Prefer an alternative antiviral where possible. If used, hold or substantially reduce tacrolimus under transplant specialist direction, check trough levels within a few days, and monitor renal function, potassium and ECG, then restore dosing after the course.
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 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 Nirmatrelvir / ritonavir with Tacrolimus?
MediHelp rates the interaction as major. Nirmatrelvir / ritonavir 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. The ritonavir-boosted nirmatrelvir combination strongly inhibits CYP3A and can raise tacrolimus exposure many-fold within days. This risks nephrotoxicity, neurotoxicity, hyperkalemia and QT prolongation. The effect persists for some days after the antiviral course ends.
How serious is the interaction between Nirmatrelvir / ritonavir 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: Prefer an alternative antiviral where possible. If used, hold or substantially reduce tacrolimus under transplant specialist direction, check trough levels within a few days, and monitor renal function, potassium and ECG, then restore dosing after the course.
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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