Drug interactions
Diltiazem + Lapatinib
Severity: Moderate
Diltiazem and Lapatinib: 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
Diltiazem, a moderate CYP3A4 inhibitor, can increase lapatinib exposure, raising risks of QT prolongation, hepatotoxicity and diarrhea.
What this interaction means in plain words
Diltiazem and Lapatinib 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.
Diltiazem belongs to Cardiovascular; Lapatinib belongs to Oncology.
Why it happens
Diltiazem inhibits CYP3A4 metabolism of lapatinib.
What to do
Monitor ECG, electrolytes and liver function, and consider an alternative non-inhibiting antihypertensive; reduce the lapatinib dose if an inhibitor cannot be avoided.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Diltiazem and Lapatinib, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Diltiazem
- Diltiazem + Flibanserin Contraindicated
- Diltiazem + Ivabradine Contraindicated
- Diltiazem + Lomitapide Contraindicated
- Diltiazem + Lonafarnib Contraindicated
- Acebutolol + Diltiazem Major
- Alfentanil + Diltiazem Major
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 Diltiazem with Lapatinib?
MediHelp rates the interaction as moderate. Diltiazem and Lapatinib 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. Diltiazem, a moderate CYP3A4 inhibitor, can increase lapatinib exposure, raising risks of QT prolongation, hepatotoxicity and diarrhea.
How serious is the interaction between Diltiazem and Lapatinib?
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 ECG, electrolytes and liver function, and consider an alternative non-inhibiting antihypertensive; reduce the lapatinib dose if an inhibitor cannot be avoided.
What other medicines interact with Diltiazem?
MediHelp also lists interactions of Diltiazem with, for example, Flibanserin, Ivabradine, Lomitapide. The full list is on the Diltiazem page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
