Drug interactions
Posaconazole + Rifabutin
Severity: Major
Posaconazole and Rifabutin: 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
Rifabutin lowers posaconazole levels, risking antifungal failure, while posaconazole raises rifabutin levels, increasing risks of uveitis, neutropenia and hepatotoxicity.
What this interaction means in plain words
Posaconazole and Rifabutin 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.
Posaconazole belongs to Anti Fungals; Rifabutin belongs to Anti Bacterial.
Why it happens
Rifabutin induces posaconazole elimination (UGT and efflux), while posaconazole inhibits CYP3A4 metabolism of rifabutin.
What to do
Avoid the combination if possible. If necessary, monitor posaconazole concentrations, blood counts and signs of uveitis, and consider reducing rifabutin dose.
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 Posaconazole
- Artemether + Posaconazole Contraindicated
- Avanafil + Posaconazole Contraindicated
- Cobimetinib + Posaconazole Contraindicated
- Conivaptan + Posaconazole Contraindicated
- Dihydroergotamine intranasal + Posaconazole Contraindicated
- Dihydroergotamine + Posaconazole Contraindicated
Other interactions of Rifabutin
- Cabotegravir + Rifabutin Contraindicated
- Lorlatinib + Rifabutin Contraindicated
- Rifabutin + Voriconazole Contraindicated
- Apixaban + Rifabutin Major
- Axitinib + Rifabutin Major
- Brexpiprazole + Rifabutin Major
Frequently asked questions
Can I take Posaconazole with Rifabutin?
MediHelp rates the interaction as major. Posaconazole and Rifabutin 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. Rifabutin lowers posaconazole levels, risking antifungal failure, while posaconazole raises rifabutin levels, increasing risks of uveitis, neutropenia and hepatotoxicity.
How serious is the interaction between Posaconazole and Rifabutin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination if possible. If necessary, monitor posaconazole concentrations, blood counts and signs of uveitis, and consider reducing rifabutin dose.
What other medicines interact with Posaconazole?
MediHelp also lists interactions of Posaconazole with, for example, Artemether, Avanafil, Cobimetinib. The full list is on the Posaconazole page.
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