Drug interactions
Rifabutin + Tamoxifen
Severity: Moderate
Rifabutin and Tamoxifen: moderate 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 induces CYP3A4 and can lower tamoxifen and N-desmethyltamoxifen concentrations. Rifampicin has produced marked reductions in tamoxifen exposure, and rifabutin, a weaker inducer, may cause a smaller but relevant reduction.
What this interaction means in plain words
Rifabutin and Tamoxifen can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Rifabutin belongs to Anti Bacterial; Tamoxifen belongs to Endocrine.
Why it happens
CYP3A4 induction by rifabutin increases tamoxifen clearance.
What to do
Monitor clinical response, and use a non-inducing alternative antimycobacterial where feasible.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Tamoxifen
- Amiodarone + Tamoxifen Major
- Anastrozole + Tamoxifen Major
- Bupropion + Tamoxifen Major
- Carbamazepine + Tamoxifen Major
- Cinacalcet + Tamoxifen Major
- Dacomitinib + Tamoxifen Major
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 Rifabutin with Tamoxifen?
MediHelp rates the interaction as moderate. Rifabutin and Tamoxifen can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Rifabutin induces CYP3A4 and can lower tamoxifen and N-desmethyltamoxifen concentrations. Rifampicin has produced marked reductions in tamoxifen exposure, and rifabutin, a weaker inducer, may cause a smaller but relevant reduction.
How serious is the interaction between Rifabutin and Tamoxifen?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor clinical response, and use a non-inducing alternative antimycobacterial where feasible.
What other medicines interact with Tamoxifen?
MediHelp also lists interactions of Tamoxifen with, for example, Amiodarone, Anastrozole, Bupropion. The full list is on the Tamoxifen page.
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