Drug interactions
Darunavir + Tamoxifen
Severity: Moderate
Darunavir 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
Darunavir, usually boosted with ritonavir or cobicistat, inhibits CYP3A4 and may alter tamoxifen metabolism. The effect on efficacy is uncertain.
What this interaction means in plain words
Darunavir 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.
Darunavir belongs to Anti Virals; Tamoxifen belongs to Endocrine.
Why it happens
Darunavir regimens inhibit CYP3A4-mediated tamoxifen N-demethylation.
What to do
Monitor for tamoxifen toxicity and consider an alternative if clinically significant.
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 Darunavir
- Alfuzosin + Darunavir Contraindicated
- Avanafil + Darunavir Contraindicated
- Darunavir + Dronedarone Contraindicated
- Darunavir + Eletriptan Contraindicated
- Darunavir + Ergotamine Contraindicated
- Darunavir + Flibanserin Contraindicated
Frequently asked questions
Can I take Darunavir with Tamoxifen?
MediHelp rates the interaction as moderate. Darunavir 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. Darunavir, usually boosted with ritonavir or cobicistat, inhibits CYP3A4 and may alter tamoxifen metabolism. The effect on efficacy is uncertain.
How serious is the interaction between Darunavir 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 for tamoxifen toxicity and consider an alternative if clinically significant.
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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