Drug interactions
Lapatinib + Posaconazole
Severity: Major
Lapatinib and Posaconazole: 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
Posaconazole inhibits CYP3A4 and can substantially raise lapatinib levels, increasing the risks of hepatotoxicity and QT prolongation. Lapatinib itself prolongs the QT interval, so the combined effect on cardiac repolarization may be additive.
What this interaction means in plain words
Lapatinib and Posaconazole 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; Posaconazole belongs to Anti Fungals.
Why it happens
CYP3A4 inhibition of lapatinib metabolism plus additive QT prolongation.
What to do
Avoid if possible; if needed, reduce the lapatinib dose according to labeling for strong CYP3A4 inhibitors. Monitor ECG, electrolytes and liver tests.
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 Posaconazole
- Artemether + Posaconazole Contraindicated
- Avanafil + Posaconazole Contraindicated
- Cobimetinib + Posaconazole Contraindicated
- Conivaptan + Posaconazole Contraindicated
- Dihydroergotamine intranasal + Posaconazole Contraindicated
- Dihydroergotamine + Posaconazole 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 Lapatinib with Posaconazole?
MediHelp rates the interaction as major. Lapatinib and Posaconazole 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. Posaconazole inhibits CYP3A4 and can substantially raise lapatinib levels, increasing the risks of hepatotoxicity and QT prolongation. Lapatinib itself prolongs the QT interval, so the combined effect on cardiac repolarization may be additive.
How serious is the interaction between Lapatinib and Posaconazole?
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 if possible; if needed, reduce the lapatinib dose according to labeling for strong CYP3A4 inhibitors. Monitor ECG, electrolytes and liver tests.
What other medicines interact with Posaconazole?
MediHelp also lists interactions of Posaconazole with, for example, Artemether, Avanafil, Cobimetinib. The full list is on the Posaconazole page.
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