Drug interactions
Lapatinib + Oxybutynin
Severity: Minor
Lapatinib and Oxybutynin: 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 weak CYP3A4 inhibitor and could modestly increase oxybutynin levels. The clinical consequence would be heightened anticholinergic effects.
What this interaction means in plain words
Lapatinib and Oxybutynin 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; Oxybutynin belongs to Genitourinary.
Why it happens
Lapatinib inhibits CYP3A4, slightly reducing oxybutynin metabolism.
What to do
Monitor for dry mouth, constipation, and confusion, and lower the oxybutynin dose if they occur.
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 Oxybutynin
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 Oxybutynin?
MediHelp rates the interaction as minor. Lapatinib and Oxybutynin 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 weak CYP3A4 inhibitor and could modestly increase oxybutynin levels. The clinical consequence would be heightened anticholinergic effects.
How serious is the interaction between Lapatinib and Oxybutynin?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for dry mouth, constipation, and confusion, and lower the oxybutynin dose if they occur.
What other medicines interact with Oxybutynin?
MediHelp also lists interactions of Oxybutynin with, for example, Bethanechol, Clozapine, Potassium chloride. The full list is on the Oxybutynin page.
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