Drug interactions
Irinotecan + Lapatinib
Severity: Major
Irinotecan and Lapatinib: major interaction.
Last updated Sources: EMA SmPC
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
Lapatinib inhibits CYP3A4 and P-glycoprotein and may raise exposure to irinotecan and its active metabolite SN-38. Diarrhea and neutropenia could be more severe, and lapatinib itself causes diarrhea.
What this interaction means in plain words
Irinotecan and Lapatinib 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.
Irinotecan belongs to Oncology; Lapatinib belongs to Oncology.
Why it happens
Lapatinib inhibits CYP3A4, P-glycoprotein and related efflux, and may reduce SN-38 clearance.
What to do
Monitor closely for severe diarrhea and neutropenia and consider reducing the irinotecan dose. Provide prompt antidiarrheal and fluid management.
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 Lapatinib
- Dofetilide + Lapatinib Contraindicated
- Ibutilide + Lapatinib Contraindicated
- Lapatinib + Pimozide Contraindicated
- Lapatinib + Saquinavir Contraindicated
- Lapatinib + Thioridazine Contraindicated
- Adagrasib + Lapatinib Major
Other interactions of Irinotecan
- Clozapine + Irinotecan Contraindicated
- Irinotecan + Sacituzumab govitecan Contraindicated
- Adenovirus types 4 and 7 live + Irinotecan Major
- Apalutamide + Irinotecan Major
- Atazanavir + Irinotecan Major
- Carbamazepine + Irinotecan Major
Frequently asked questions
Can I take Irinotecan with Lapatinib?
MediHelp rates the interaction as major. Irinotecan and Lapatinib 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. Lapatinib inhibits CYP3A4 and P-glycoprotein and may raise exposure to irinotecan and its active metabolite SN-38. Diarrhea and neutropenia could be more severe, and lapatinib itself causes diarrhea.
How serious is the interaction between Irinotecan and Lapatinib?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor closely for severe diarrhea and neutropenia and consider reducing the irinotecan dose. Provide prompt antidiarrheal and fluid management.
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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