Drug interactions
Tamoxifen + Topotecan
Severity: Moderate
Tamoxifen and Topotecan: 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
Tamoxifen may inhibit P-glycoprotein and raise topotecan exposure, particularly oral topotecan. Higher exposure could increase myelosuppression and gastrointestinal toxicity.
What this interaction means in plain words
Tamoxifen and Topotecan 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.
Tamoxifen belongs to Endocrine; Topotecan belongs to Oncology.
Why it happens
Tamoxifen inhibits P-glycoprotein efflux, increasing topotecan absorption and reducing its elimination.
What to do
Avoid with oral topotecan if possible. With intravenous topotecan, monitor blood counts closely and reduce the dose if marked myelosuppression occurs.
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 Topotecan
- Adenovirus types 4 and 7 live + Topotecan Contraindicated
- Amiodarone + Topotecan Major
- Cisplatin + Topotecan Major
- Cobicistat + Topotecan Major
- Cyclosporine + Topotecan Major
- Cyclosporin + Topotecan Major
Frequently asked questions
Can I take Tamoxifen with Topotecan?
MediHelp rates the interaction as moderate. Tamoxifen and Topotecan 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. Tamoxifen may inhibit P-glycoprotein and raise topotecan exposure, particularly oral topotecan. Higher exposure could increase myelosuppression and gastrointestinal toxicity.
How serious is the interaction between Tamoxifen and Topotecan?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid with oral topotecan if possible. With intravenous topotecan, monitor blood counts closely and reduce the dose if marked myelosuppression occurs.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
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