Drug interactions
Lapatinib + Loperamide
Severity: Moderate
Lapatinib and Loperamide: 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
Lapatinib may raise loperamide exposure by blocking its efflux, and lapatinib itself prolongs the QT interval. Since loperamide is often used for lapatinib-induced diarrhea, cardiac effects deserve attention.
What this interaction means in plain words
Lapatinib and Loperamide 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; Loperamide belongs to Gastrointestinal Tract.
Why it happens
Lapatinib inhibits P-glycoprotein, increasing loperamide absorption and CNS penetration, with additive QT effects.
What to do
Use loperamide at standard labeled doses for diarrhea and avoid exceeding the maximum. Monitor ECG and electrolytes in patients at risk of QT prolongation.
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 Loperamide
Other interactions of Lapatinib
- Dofetilide + Lapatinib Contraindicated
- Ibutilide + Lapatinib Contraindicated
- Lapatinib + Pimozide Contraindicated
- Lapatinib + Saquinavir Contraindicated
- Lapatinib + Thioridazine Contraindicated
- Adagrasib + Lapatinib Major
Frequently asked questions
Can I take Lapatinib with Loperamide?
MediHelp rates the interaction as moderate. Lapatinib and Loperamide 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 may raise loperamide exposure by blocking its efflux, and lapatinib itself prolongs the QT interval. Since loperamide is often used for lapatinib-induced diarrhea, cardiac effects deserve attention.
How serious is the interaction between Lapatinib and Loperamide?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use loperamide at standard labeled doses for diarrhea and avoid exceeding the maximum. Monitor ECG and electrolytes in patients at risk of QT prolongation.
What other medicines interact with Loperamide?
MediHelp also lists interactions of Loperamide with, for example, Amiodarone, Amisulpride, Anagrelide. The full list is on the Loperamide page.
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