Drug interactions
Lopinavir + Tamoxifen
Severity: Moderate
Lopinavir 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
Lopinavir boosted with ritonavir inhibits CYP3A4 and may change tamoxifen metabolism. Both agents can also affect the QT interval, though the evidence for the pair is limited.
What this interaction means in plain words
Lopinavir 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.
Lopinavir belongs to Anti Virals; Tamoxifen belongs to Endocrine.
Why it happens
CYP3A4 inhibition reduces tamoxifen N-demethylation, with possible additive QT effects.
What to do
Monitor the clinical response to tamoxifen and the QTc. Consider an alternative antiretroviral if 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 Lopinavir
- Alfuzosin + Lopinavir Contraindicated
- Avanafil + Lopinavir Contraindicated
- Cisapride + Lopinavir Contraindicated
- Dronedarone + Lopinavir Contraindicated
- Eletriptan + Lopinavir Contraindicated
- Eplerenone + Lopinavir Contraindicated
Frequently asked questions
Can I take Lopinavir with Tamoxifen?
MediHelp rates the interaction as moderate. Lopinavir 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. Lopinavir boosted with ritonavir inhibits CYP3A4 and may change tamoxifen metabolism. Both agents can also affect the QT interval, though the evidence for the pair is limited.
How serious is the interaction between Lopinavir 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 the clinical response to tamoxifen and the QTc. Consider an alternative antiretroviral if 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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