Drug interactions
Mitotane + Tamoxifen
Severity: Major
Mitotane and Tamoxifen: major interaction.
Last updated Sources: US FDA label
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
Mitotane is a strong CYP3A4 inducer and substantially lowers tamoxifen and metabolite exposure. This can compromise the antiestrogen effect of tamoxifen.
What this interaction means in plain words
Mitotane and Tamoxifen can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Mitotane belongs to Oncology; Tamoxifen belongs to Endocrine.
Why it happens
Mitotane induces CYP3A4 and accelerates tamoxifen clearance.
What to do
Avoid the combination and consider a non-CYP3A4-dependent endocrine option. Induction persists for weeks after mitotane is stopped.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
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 Mitotane
- Doravirine + Mitotane Contraindicated
- Fostemsavir + Mitotane Contraindicated
- Lorlatinib + Mitotane Contraindicated
- Abiraterone + Mitotane Major
- Apixaban + Mitotane Major
- Aprepitant + Mitotane Major
Frequently asked questions
Can I take Mitotane with Tamoxifen?
MediHelp rates the interaction as major. Mitotane and Tamoxifen can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Mitotane is a strong CYP3A4 inducer and substantially lowers tamoxifen and metabolite exposure. This can compromise the antiestrogen effect of tamoxifen.
How serious is the interaction between Mitotane and Tamoxifen?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination and consider a non-CYP3A4-dependent endocrine option. Induction persists for weeks after mitotane is stopped.
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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