Drug interactions
Etravirine + Tamoxifen
Severity: Moderate
Etravirine 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
Etravirine is a CYP3A4 and CYP2C19 inducer and a mild CYP2C9 inhibitor, so its effect on tamoxifen and its active metabolites is unpredictable. Induction could lower tamoxifen and endoxifen exposure, with possible loss of efficacy.
What this interaction means in plain words
Etravirine 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.
Etravirine belongs to Anti Virals; Tamoxifen belongs to Endocrine.
Why it happens
Etravirine modulates CYP3A4, CYP2C9 and CYP2C19, altering tamoxifen metabolism; the net effect is not well established.
What to do
Monitor for reduced tamoxifen efficacy or increased adverse effects. Consider an alternative antiretroviral if the combination is a concern.
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 Etravirine
- Efavirenz + Etravirine Contraindicated
- Etravirine + Isavuconazole Contraindicated
- Amobarbital + Etravirine Major
- Apalutamide + Etravirine Major
- Carbamazepine + Etravirine Major
- Cobicistat + Etravirine Major
Frequently asked questions
Can I take Etravirine with Tamoxifen?
MediHelp rates the interaction as moderate. Etravirine 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. Etravirine is a CYP3A4 and CYP2C19 inducer and a mild CYP2C9 inhibitor, so its effect on tamoxifen and its active metabolites is unpredictable. Induction could lower tamoxifen and endoxifen exposure, with possible loss of efficacy.
How serious is the interaction between Etravirine 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 reduced tamoxifen efficacy or increased adverse effects. Consider an alternative antiretroviral if the combination is a concern.
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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