Drug interactions
Isoniazid + Lapatinib
Severity: Moderate
Isoniazid and Lapatinib: moderate 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
Lapatinib is a CYP3A4 substrate and isoniazid may inhibit this enzyme weakly, which could increase lapatinib exposure. Lapatinib carries hepatotoxicity and QT prolongation risks, and isoniazid is also hepatotoxic.
What this interaction means in plain words
Isoniazid and Lapatinib can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Isoniazid belongs to Anti Bacterial; Lapatinib belongs to Oncology.
Why it happens
Weak CYP3A4 inhibition by isoniazid and additive hepatotoxicity.
What to do
Monitor liver function tests and ECG during combined use. Reduce the lapatinib dose or stop one agent if hepatotoxicity develops.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Isoniazid
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 Isoniazid with Lapatinib?
MediHelp rates the interaction as moderate. Isoniazid and Lapatinib can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Lapatinib is a CYP3A4 substrate and isoniazid may inhibit this enzyme weakly, which could increase lapatinib exposure. Lapatinib carries hepatotoxicity and QT prolongation risks, and isoniazid is also hepatotoxic.
How serious is the interaction between Isoniazid and Lapatinib?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor liver function tests and ECG during combined use. Reduce the lapatinib dose or stop one agent if hepatotoxicity develops.
What other medicines interact with Isoniazid?
MediHelp also lists interactions of Isoniazid with, for example, Bacillus calmette-guerin substrain tice, Benzhydrocodone / acetaminophen, Carbamazepine. The full list is on the Isoniazid page.
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