Drug interactions
Fosaprepitant + Tamoxifen
Severity: Minor
Fosaprepitant and Tamoxifen: minor 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
Aprepitant, the active form of fosaprepitant, is a moderate CYP3A4 inhibitor. A single-dose or short course given with chemotherapy is unlikely to have a lasting effect on tamoxifen activation.
What this interaction means in plain words
Fosaprepitant and Tamoxifen have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Fosaprepitant belongs to Gastrointestinal Tract; Tamoxifen belongs to Endocrine.
Why it happens
Transient CYP3A4 inhibition reduces tamoxifen conversion to N-desmethyltamoxifen.
What to do
No dose adjustment is needed for short antiemetic courses.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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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 Fosaprepitant
- Flibanserin + Fosaprepitant Contraindicated
- Fosaprepitant + Pimozide Contraindicated
- Alprazolam + Fosaprepitant Moderate
- Amiodarone + Fosaprepitant Moderate
- Amobarbital + Fosaprepitant Moderate
- Apalutamide + Fosaprepitant Moderate
Frequently asked questions
Can I take Fosaprepitant with Tamoxifen?
MediHelp rates the interaction as minor. Fosaprepitant and Tamoxifen have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Aprepitant, the active form of fosaprepitant, is a moderate CYP3A4 inhibitor. A single-dose or short course given with chemotherapy is unlikely to have a lasting effect on tamoxifen activation.
How serious is the interaction between Fosaprepitant and Tamoxifen?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No dose adjustment is needed for short antiemetic courses.
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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