Drug interactions
Lapatinib + Metronidazole
Severity: Minor
Lapatinib and Metronidazole: minor 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 higher exposure may increase diarrhea, hepatotoxicity and QT prolongation. Metronidazole is only a weak CYP3A4 inhibitor, so any increase is probably small.
What this interaction means in plain words
Lapatinib and Metronidazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Lapatinib belongs to Oncology; Metronidazole belongs to Anti Parasitic.
Why it happens
Possible weak inhibition of CYP3A4-mediated lapatinib metabolism by metronidazole.
What to do
No dose adjustment is usually needed; monitor liver tests and ECG if other QT-prolonging drugs are co-prescribed.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Metronidazole
- Ethanol + Metronidazole Contraindicated
- Metronidazole + Pimozide Contraindicated
- Amiodarone + Metronidazole Major
- Disulfiram + Metronidazole Major
- Ergotamine + Metronidazole Major
- Lomitapide + Metronidazole Major
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 Metronidazole?
MediHelp rates the interaction as minor. Lapatinib and Metronidazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Lapatinib is a CYP3A4 substrate, and higher exposure may increase diarrhea, hepatotoxicity and QT prolongation. Metronidazole is only a weak CYP3A4 inhibitor, so any increase is probably small.
How serious is the interaction between Lapatinib and Metronidazole?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No dose adjustment is usually needed; monitor liver tests and ECG if other QT-prolonging drugs are co-prescribed.
What other medicines interact with Metronidazole?
MediHelp also lists interactions of Metronidazole with, for example, Ethanol, Pimozide, Amiodarone. The full list is on the Metronidazole page.
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