Drug interactions
Fosaprepitant + Lapatinib
Severity: Moderate
Fosaprepitant 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
Fosaprepitant is converted to aprepitant, a moderate CYP3A4 inhibitor, and a single dose causes a short-lived inhibition. Lapatinib exposure may rise modestly for several days.
What this interaction means in plain words
Fosaprepitant 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.
Fosaprepitant belongs to Gastrointestinal Tract; Lapatinib belongs to Oncology.
Why it happens
Aprepitant transiently inhibits CYP3A4, reducing lapatinib metabolism.
What to do
Monitor for lapatinib toxicity such as diarrhea and QT changes after fosaprepitant dosing; no routine dose change is needed for a single 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
Other interactions of Fosaprepitant
- Flibanserin + Fosaprepitant Contraindicated
- Fosaprepitant + Pimozide Contraindicated
- Alprazolam + Fosaprepitant Moderate
- Amiodarone + Fosaprepitant Moderate
- Amobarbital + Fosaprepitant Moderate
- Apalutamide + Fosaprepitant Moderate
Frequently asked questions
Can I take Fosaprepitant with Lapatinib?
MediHelp rates the interaction as moderate. Fosaprepitant 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. Fosaprepitant is converted to aprepitant, a moderate CYP3A4 inhibitor, and a single dose causes a short-lived inhibition. Lapatinib exposure may rise modestly for several days.
How serious is the interaction between Fosaprepitant 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 lapatinib toxicity such as diarrhea and QT changes after fosaprepitant dosing; no routine dose change is needed for a single 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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