Drug interactions
Conivaptan + Lapatinib
Severity: Moderate
Conivaptan 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
Conivaptan is a CYP3A4 inhibitor and may raise lapatinib concentrations. Higher lapatinib exposure increases the risk of QT prolongation, hepatotoxicity and diarrhea.
What this interaction means in plain words
Conivaptan 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.
Why it happens
Conivaptan inhibits CYP3A4, reducing lapatinib metabolism.
What to do
Avoid the combination if possible, as conivaptan labeling advises against strong CYP3A4 interactions. If used, monitor ECG and liver tests and consider reducing the lapatinib dose.
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 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 Conivaptan with Lapatinib?
MediHelp rates the interaction as moderate. Conivaptan 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. Conivaptan is a CYP3A4 inhibitor and may raise lapatinib concentrations. Higher lapatinib exposure increases the risk of QT prolongation, hepatotoxicity and diarrhea.
How serious is the interaction between Conivaptan 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: Avoid the combination if possible, as conivaptan labeling advises against strong CYP3A4 interactions. If used, monitor ECG and liver tests and consider reducing the lapatinib dose.
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.
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