Drug interactions
Fesoterodine + Lapatinib
Severity: Moderate
Fesoterodine 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 inhibits CYP3A4 and may raise exposure to the active metabolite of fesoterodine. This could increase antimuscarinic adverse effects, particularly in patients with reduced renal function or CYP2D6 poor metabolism.
What this interaction means in plain words
Fesoterodine 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.
Fesoterodine belongs to Genitourinary; Lapatinib belongs to Oncology.
Why it happens
Inhibition of CYP3A4 by lapatinib reduces clearance of the fesoterodine active metabolite.
What to do
Monitor for antimuscarinic effects such as dry mouth, constipation and urinary retention. Limit fesoterodine to 4 mg daily if adverse effects develop.
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 Fesoterodine
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 Fesoterodine with Lapatinib?
MediHelp rates the interaction as moderate. Fesoterodine 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 inhibits CYP3A4 and may raise exposure to the active metabolite of fesoterodine. This could increase antimuscarinic adverse effects, particularly in patients with reduced renal function or CYP2D6 poor metabolism.
How serious is the interaction between Fesoterodine 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 for antimuscarinic effects such as dry mouth, constipation and urinary retention. Limit fesoterodine to 4 mg daily if adverse effects develop.
What other medicines interact with Fesoterodine?
MediHelp also lists interactions of Fesoterodine with, for example, Bethanechol, Clozapine, Levoketoconazole. The full list is on the Fesoterodine page.
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