Drug interactions
Clarithromycin + Lapatinib
Severity: Major
Clarithromycin and Lapatinib: major interaction.
Last updated Sources: US FDA label
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
Clarithromycin, a strong CYP3A4 inhibitor, can substantially raise lapatinib concentrations. Lapatinib itself prolongs the QT interval and can cause hepatotoxicity and diarrhea, so higher exposure increases these risks.
What this interaction means in plain words
Clarithromycin 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.
Clarithromycin belongs to Anti Bacterial; Lapatinib belongs to Oncology.
Why it happens
Strong CYP3A4 inhibition by clarithromycin reduces lapatinib metabolism, with additive QT effects.
What to do
Avoid strong CYP3A4 inhibitors with lapatinib and choose a different antibiotic. If unavoidable, consider a lapatinib dose reduction per labeling and monitor the ECG and liver function.
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 Clarithromycin
- Astemizole + Clarithromycin Contraindicated
- Avanafil + Clarithromycin Contraindicated
- Cisapride + Clarithromycin Contraindicated
- Clarithromycin + Colchicine Contraindicated
- Clarithromycin + Conivaptan Contraindicated
- Clarithromycin + Dihydroergotamine Contraindicated
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 Clarithromycin with Lapatinib?
MediHelp rates the interaction as major. Clarithromycin 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. Clarithromycin, a strong CYP3A4 inhibitor, can substantially raise lapatinib concentrations. Lapatinib itself prolongs the QT interval and can cause hepatotoxicity and diarrhea, so higher exposure increases these risks.
How serious is the interaction between Clarithromycin 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: Avoid strong CYP3A4 inhibitors with lapatinib and choose a different antibiotic. If unavoidable, consider a lapatinib dose reduction per labeling and monitor the ECG and liver function.
What other medicines interact with Clarithromycin?
MediHelp also lists interactions of Clarithromycin with, for example, Astemizole, Avanafil, Cisapride. The full list is on the Clarithromycin page.
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