Drug interactions
Nirmatrelvir / ritonavir + Sirolimus
Severity: Major
Nirmatrelvir / ritonavir and Sirolimus: 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
Ritonavir-boosted nirmatrelvir strongly inhibits CYP3A4 and P-gp, causing large rises in sirolimus concentrations. This can lead to serious toxicity, including kidney injury, cytopenias and infection.
What this interaction means in plain words
Nirmatrelvir / ritonavir and Sirolimus 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
Potent inhibition of CYP3A4 and P-glycoprotein by ritonavir reduces sirolimus clearance.
What to do
Prefer an alternative antiviral such as remdesivir. If the combination is necessary, withhold sirolimus during treatment per transplant team guidance and check trough levels during and after therapy.
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 Sirolimus
- Adenovirus types 4 and 7 live + Sirolimus Contraindicated
- Bcg vaccine live + Sirolimus Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Sirolimus Contraindicated
- Ketoconazole + Sirolimus Contraindicated
- Levoketoconazole + Sirolimus Contraindicated
- Measles mumps and rubella vaccine live + Sirolimus Contraindicated
Frequently asked questions
Can I take Nirmatrelvir / ritonavir with Sirolimus?
MediHelp rates the interaction as major. Nirmatrelvir / ritonavir and Sirolimus 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. Ritonavir-boosted nirmatrelvir strongly inhibits CYP3A4 and P-gp, causing large rises in sirolimus concentrations. This can lead to serious toxicity, including kidney injury, cytopenias and infection.
How serious is the interaction between Nirmatrelvir / ritonavir and Sirolimus?
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 such as remdesivir. If the combination is necessary, withhold sirolimus during treatment per transplant team guidance and check trough levels during and after therapy.
What other medicines interact with Sirolimus?
MediHelp also lists interactions of Sirolimus with, for example, Adenovirus types 4 and 7 live, Bcg vaccine live, Influenza virus vaccine quadrivalent intranasal. The full list is on the Sirolimus page.
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