Drug interactions
Lapatinib + Lefamulin
Severity: Major
Lapatinib and Lefamulin: major 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
Lefamulin is a CYP3A4 inhibitor and may raise lapatinib exposure. Both drugs prolong the QT interval, so the combination increases the risk of serious arrhythmia including torsades de pointes.
What this interaction means in plain words
Lapatinib and Lefamulin 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 belongs to Oncology; Lefamulin belongs to Anti Bacterial.
Why it happens
Lefamulin inhibits CYP3A4 metabolism of lapatinib, with additive QT prolongation.
What to do
Use an alternative antibiotic if feasible. If used, obtain a baseline ECG, correct potassium and magnesium, and monitor QTc.
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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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 Lefamulin
- Lefamulin + Methadone Contraindicated
- Lefamulin + Pimavanserin Contraindicated
- Lefamulin + Pimozide Contraindicated
- Lefamulin + Quinidine Contraindicated
- Alfuzosin + Lefamulin Major
- Amiodarone + Lefamulin Major
Frequently asked questions
Can I take Lapatinib with Lefamulin?
MediHelp rates the interaction as major. Lapatinib and Lefamulin 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. Lefamulin is a CYP3A4 inhibitor and may raise lapatinib exposure. Both drugs prolong the QT interval, so the combination increases the risk of serious arrhythmia including torsades de pointes.
How serious is the interaction between Lapatinib and Lefamulin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use an alternative antibiotic if feasible. If used, obtain a baseline ECG, correct potassium and magnesium, and monitor QTc.
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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