Drug interactions
Lapatinib + Tolterodine
Severity: Moderate
Lapatinib and Tolterodine: 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 can increase tolterodine exposure. Both drugs can prolong the QT interval, so higher tolterodine levels add to arrhythmia risk. Anticholinergic effects may also be more pronounced.
What this interaction means in plain words
Lapatinib and Tolterodine 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 belongs to Oncology; Tolterodine belongs to Genitourinary.
Why it happens
Lapatinib inhibits CYP3A4 metabolism of tolterodine, with additive QT effects.
What to do
Monitor the ECG and electrolytes, particularly in patients with other QT risk factors. Reduce the tolterodine dose if anticholinergic effects emerge.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Lapatinib and Tolterodine, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Tolterodine
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 Tolterodine?
MediHelp rates the interaction as moderate. Lapatinib and Tolterodine 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 can increase tolterodine exposure. Both drugs can prolong the QT interval, so higher tolterodine levels add to arrhythmia risk. Anticholinergic effects may also be more pronounced.
How serious is the interaction between Lapatinib and Tolterodine?
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 the ECG and electrolytes, particularly in patients with other QT risk factors. Reduce the tolterodine dose if anticholinergic effects emerge.
What other medicines interact with Tolterodine?
MediHelp also lists interactions of Tolterodine with, for example, Clarithromycin, Clozapine, Cobicistat. The full list is on the Tolterodine page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
