Drug interactions
Nelfinavir + Tamoxifen
Severity: Moderate
Nelfinavir 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
Nelfinavir inhibits CYP3A4 and may alter tamoxifen metabolite formation. The clinical effect on tamoxifen efficacy is uncertain.
What this interaction means in plain words
Nelfinavir 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.
Nelfinavir belongs to Anti Virals; Tamoxifen belongs to Endocrine.
Why it happens
CYP3A4 inhibition reduces tamoxifen N-demethylation.
What to do
Consider an alternative antiretroviral if feasible. If combined, monitor clinical response and tolerability.
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 Nelfinavir
- Alfuzosin + Nelfinavir Contraindicated
- Avanafil + Nelfinavir Contraindicated
- Dronedarone + Nelfinavir Contraindicated
- Eletriptan + Nelfinavir Contraindicated
- Ergotamine + Nelfinavir Contraindicated
- Flibanserin + Nelfinavir Contraindicated
Frequently asked questions
Can I take Nelfinavir with Tamoxifen?
MediHelp rates the interaction as moderate. Nelfinavir 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. Nelfinavir inhibits CYP3A4 and may alter tamoxifen metabolite formation. The clinical effect on tamoxifen efficacy is uncertain.
How serious is the interaction between Nelfinavir 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: Consider an alternative antiretroviral if feasible. If combined, monitor clinical response and tolerability.
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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