Drug interactions
Lapatinib + Mestranol
Severity: Minor
Lapatinib and Mestranol: 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 inhibits CYP3A4 and P-gp, which may modestly raise exposure to mestranol, a prodrug of ethinylestradiol. Estrogenic adverse effects may increase slightly.
What this interaction means in plain words
Lapatinib and Mestranol have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Lapatinib inhibits CYP3A4 and P-gp, reducing the clearance of estrogen.
What to do
No routine adjustment is needed; monitor for estrogen-related adverse effects. Note that estrogens are generally unsuitable in hormone-sensitive breast cancer.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Lapatinib and Mestranol, 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 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 Mestranol?
MediHelp rates the interaction as minor. Lapatinib and Mestranol 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 inhibits CYP3A4 and P-gp, which may modestly raise exposure to mestranol, a prodrug of ethinylestradiol. Estrogenic adverse effects may increase slightly.
How serious is the interaction between Lapatinib and Mestranol?
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 routine adjustment is needed; monitor for estrogen-related adverse effects. Note that estrogens are generally unsuitable in hormone-sensitive breast cancer.
What other medicines interact with Lapatinib?
MediHelp also lists interactions of Lapatinib with, for example, Dofetilide, Ibutilide, Pimozide. The full list is on the Lapatinib 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.
