Drug interactions
Crizotinib + Tamoxifen
Severity: Minor
Crizotinib 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
Crizotinib is a moderate CYP3A4 inhibitor and may slow the N-demethylation of tamoxifen. Since the active endoxifen pathway depends mainly on CYP2D6, the clinical effect on efficacy is probably small, but exposure to parent drug may shift.
What this interaction means in plain words
Crizotinib 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.
Crizotinib belongs to Oncology; Tamoxifen belongs to Endocrine.
Why it happens
Crizotinib inhibits CYP3A4, reducing tamoxifen conversion to N-desmethyltamoxifen.
What to do
No dose change is usually needed; monitor for tamoxifen adverse effects and for crizotinib-related QT effects and bradycardia.
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 Crizotinib
- Crizotinib + Flibanserin Contraindicated
- Crizotinib + Lomitapide Contraindicated
- Crizotinib + Lonafarnib Contraindicated
- Crizotinib + Pimozide Contraindicated
- Crizotinib + Saquinavir Contraindicated
- Crizotinib + Thioridazine Contraindicated
Frequently asked questions
Can I take Crizotinib with Tamoxifen?
MediHelp rates the interaction as minor. Crizotinib 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. Crizotinib is a moderate CYP3A4 inhibitor and may slow the N-demethylation of tamoxifen. Since the active endoxifen pathway depends mainly on CYP2D6, the clinical effect on efficacy is probably small, but exposure to parent drug may shift.
How serious is the interaction between Crizotinib 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 change is usually needed; monitor for tamoxifen adverse effects and for crizotinib-related QT effects and bradycardia.
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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