Drug interactions
Lapatinib + Larotrectinib
Severity: Minor
Lapatinib and Larotrectinib: 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
Larotrectinib is a CYP3A4 substrate and a weak CYP3A4 inhibitor, so it may raise lapatinib levels slightly. Increased lapatinib exposure might worsen diarrhea, hepatotoxicity and QT effects.
What this interaction means in plain words
Lapatinib and Larotrectinib have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Lapatinib belongs to Oncology; Larotrectinib belongs to Oncology.
Why it happens
Larotrectinib weakly inhibits CYP3A4, decreasing lapatinib metabolism.
What to do
Monitor liver tests, QTc and gastrointestinal tolerance. Reduce the lapatinib dose if toxicity occurs.
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 Lapatinib
- Dofetilide + Lapatinib Contraindicated
- Ibutilide + Lapatinib Contraindicated
- Lapatinib + Pimozide Contraindicated
- Lapatinib + Saquinavir Contraindicated
- Lapatinib + Thioridazine Contraindicated
- Adagrasib + Lapatinib Major
Other interactions of Larotrectinib
Frequently asked questions
Can I take Lapatinib with Larotrectinib?
MediHelp rates the interaction as minor. Lapatinib and Larotrectinib have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Larotrectinib is a CYP3A4 substrate and a weak CYP3A4 inhibitor, so it may raise lapatinib levels slightly. Increased lapatinib exposure might worsen diarrhea, hepatotoxicity and QT effects.
How serious is the interaction between Lapatinib and Larotrectinib?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor liver tests, QTc and gastrointestinal tolerance. Reduce the lapatinib dose if toxicity occurs.
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.
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