Drug interactions
Bosentan + Nirmatrelvir / ritonavir
Severity: Major
Bosentan and Nirmatrelvir / ritonavir: 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
Ritonavir strongly inhibits CYP3A4, and a short course can markedly raise bosentan trough levels. This increases the risk of hepatotoxicity, hypotension and edema.
What this interaction means in plain words
Bosentan and Nirmatrelvir / ritonavir 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 inhibits CYP3A4 and hepatic uptake transporters, reducing bosentan clearance.
What to do
Discontinue bosentan at least 36 hours before starting nirmatrelvir/ritonavir and restart about 10 days after starting. Monitor blood pressure and liver enzymes.
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 Bosentan
- Bosentan + Cyclosporin Contraindicated
- Bosentan + Glibenclamide Contraindicated
- Bosentan + Glyburide-metformin Contraindicated
- Bosentan + Lonafarnib Contraindicated
- Bosentan + Sparsentan Contraindicated
- Artemether / lumefantrine + Bosentan Major
Frequently asked questions
Can I take Bosentan with Nirmatrelvir / ritonavir?
MediHelp rates the interaction as major. Bosentan and Nirmatrelvir / ritonavir 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 strongly inhibits CYP3A4, and a short course can markedly raise bosentan trough levels. This increases the risk of hepatotoxicity, hypotension and edema.
How serious is the interaction between Bosentan and Nirmatrelvir / ritonavir?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Discontinue bosentan at least 36 hours before starting nirmatrelvir/ritonavir and restart about 10 days after starting. Monitor blood pressure and liver enzymes.
What other medicines interact with Bosentan?
MediHelp also lists interactions of Bosentan with, for example, Cyclosporin, Glibenclamide, Glyburide-metformin. The full list is on the Bosentan page.
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