Drug interactions
Lorlatinib + Tamoxifen
Severity: Moderate
Lorlatinib 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
Lorlatinib induces CYP3A4, which may lower exposure to tamoxifen and its N-desmethyl metabolite. Because endoxifen formation depends mainly on CYP2D6, the net effect on efficacy is uncertain.
What this interaction means in plain words
Lorlatinib 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.
Lorlatinib belongs to Oncology; Tamoxifen belongs to Endocrine.
Why it happens
Lorlatinib induction of CYP3A4 increases clearance of tamoxifen.
What to do
Monitor for reduced tamoxifen efficacy; consider an alternative endocrine therapy if lack of response is suspected.
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 Lorlatinib
- Amobarbital + Lorlatinib Contraindicated
- Apalutamide + Lorlatinib Contraindicated
- Butabarbital + Lorlatinib Contraindicated
- Carbamazepine + Lorlatinib Contraindicated
- Enzalutamide + Lorlatinib Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
Frequently asked questions
Can I take Lorlatinib with Tamoxifen?
MediHelp rates the interaction as moderate. Lorlatinib 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. Lorlatinib induces CYP3A4, which may lower exposure to tamoxifen and its N-desmethyl metabolite. Because endoxifen formation depends mainly on CYP2D6, the net effect on efficacy is uncertain.
How serious is the interaction between Lorlatinib 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: Monitor for reduced tamoxifen efficacy; consider an alternative endocrine therapy if lack of response is suspected.
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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