Drug interactions
Atazanavir + Lapatinib
Severity: Major
Atazanavir 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
Atazanavir is a strong CYP3A4 inhibitor and can substantially raise lapatinib exposure. This increases the risk of QT prolongation, hepatotoxicity and diarrhea.
What this interaction means in plain words
Atazanavir 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.
Atazanavir belongs to Anti Virals; Lapatinib belongs to Oncology.
Why it happens
Atazanavir inhibits CYP3A4, reducing lapatinib metabolism.
What to do
Avoid the combination if possible. If unavoidable, reduce the lapatinib dose as recommended in labeling for strong CYP3A4 inhibitors and monitor 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 Lapatinib
- Dofetilide + Lapatinib Contraindicated
- Ibutilide + Lapatinib Contraindicated
- Lapatinib + Pimozide Contraindicated
- Lapatinib + Saquinavir Contraindicated
- Lapatinib + Thioridazine Contraindicated
- Adagrasib + Lapatinib Major
Other interactions of Atazanavir
- Alfuzosin + Atazanavir Contraindicated
- Atazanavir + Avanafil Contraindicated
- Atazanavir + Dronedarone Contraindicated
- Atazanavir + Eletriptan Contraindicated
- Atazanavir + Eplerenone Contraindicated
- Atazanavir + Ergotamine Contraindicated
Frequently asked questions
Can I take Atazanavir with Lapatinib?
MediHelp rates the interaction as major. Atazanavir 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. Atazanavir is a strong CYP3A4 inhibitor and can substantially raise lapatinib exposure. This increases the risk of QT prolongation, hepatotoxicity and diarrhea.
How serious is the interaction between Atazanavir 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 the combination if possible. If unavoidable, reduce the lapatinib dose as recommended in labeling for strong CYP3A4 inhibitors and monitor ECG and liver function.
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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