Drug interactions
Lapatinib + Rifabutin
Severity: Major
Lapatinib and Rifabutin: 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
Rifabutin induces CYP3A4 and can lower lapatinib concentrations, which may reduce anticancer efficacy. The induction effect of rifabutin is weaker than that of rifampin but is still clinically relevant.
What this interaction means in plain words
Lapatinib and Rifabutin 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; Rifabutin belongs to Anti Bacterial.
Why it happens
Rifabutin induces CYP3A4, increasing the metabolism of lapatinib.
What to do
Use a non-inducing alternative to rifabutin if possible. If it cannot be avoided, the lapatinib dose may need to be titrated upward under labeling guidance with close monitoring.
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 Rifabutin
- Cabotegravir + Rifabutin Contraindicated
- Lorlatinib + Rifabutin Contraindicated
- Rifabutin + Voriconazole Contraindicated
- Apixaban + Rifabutin Major
- Axitinib + Rifabutin Major
- Brexpiprazole + Rifabutin Major
Frequently asked questions
Can I take Lapatinib with Rifabutin?
MediHelp rates the interaction as major. Lapatinib and Rifabutin 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. Rifabutin induces CYP3A4 and can lower lapatinib concentrations, which may reduce anticancer efficacy. The induction effect of rifabutin is weaker than that of rifampin but is still clinically relevant.
How serious is the interaction between Lapatinib and Rifabutin?
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 a non-inducing alternative to rifabutin if possible. If it cannot be avoided, the lapatinib dose may need to be titrated upward under labeling guidance with close monitoring.
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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