Drug interactions
Lapatinib + Tucatinib
Severity: Moderate
Lapatinib and Tucatinib: 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
Tucatinib inhibits CYP3A4 and may increase lapatinib exposure. Lapatinib may also affect tucatinib levels, and both agents can cause diarrhea and hepatotoxicity.
What this interaction means in plain words
Lapatinib and Tucatinib 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.
Lapatinib belongs to Oncology; Tucatinib belongs to Oncology.
Why it happens
Tucatinib inhibits CYP3A4, reducing lapatinib metabolism.
What to do
Monitor liver function and for diarrhea. Reduce the lapatinib dose if toxicity develops.
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 Lapatinib
- Dofetilide + Lapatinib Contraindicated
- Ibutilide + Lapatinib Contraindicated
- Lapatinib + Pimozide Contraindicated
- Lapatinib + Saquinavir Contraindicated
- Lapatinib + Thioridazine Contraindicated
- Adagrasib + Lapatinib Major
Other interactions of Tucatinib
- Cisapride + Tucatinib Contraindicated
- Eletriptan + Tucatinib Contraindicated
- Ergotamine + Tucatinib Contraindicated
- Flibanserin + Tucatinib Contraindicated
- Ranolazine + Tucatinib Contraindicated
- Amobarbital + Tucatinib Major
Frequently asked questions
Can I take Lapatinib with Tucatinib?
MediHelp rates the interaction as moderate. Lapatinib and Tucatinib 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. Tucatinib inhibits CYP3A4 and may increase lapatinib exposure. Lapatinib may also affect tucatinib levels, and both agents can cause diarrhea and hepatotoxicity.
How serious is the interaction between Lapatinib and Tucatinib?
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 liver function and for diarrhea. Reduce the lapatinib dose if toxicity develops.
What other medicines interact with Lapatinib?
MediHelp also lists interactions of Lapatinib with, for example, Dofetilide, Ibutilide, Pimozide. The full list is on the Lapatinib page.
Full monographs, dosing and an interaction checker in the MediHelp app
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