Drug interactions
Fosaprepitant + Warfarin
Severity: Moderate
Fosaprepitant and Warfarin: 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, a prodrug of aprepitant, can lower INR in patients on warfarin, which may reduce anticoagulation and raise clot risk. The change usually appears several days after a chemotherapy cycle.
What this interaction means in plain words
Fosaprepitant and Warfarin 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; Warfarin belongs to Cardiovascular.
Why it happens
Aprepitant induces CYP2C9 and so increases the clearance of S-warfarin.
What to do
Check INR in the two weeks after each fosaprepitant dose, especially at days 7 to 10. Adjust warfarin as needed.
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 Warfarin
- Defibrotide + Warfarin Contraindicated
- Ketorolac + Warfarin Contraindicated
- Abciximab + Warfarin Major
- Acetylsalicylic acid + Warfarin Major
- Adagrasib + Warfarin Major
- Amiodarone + Warfarin 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 Warfarin?
MediHelp rates the interaction as moderate. Fosaprepitant and Warfarin 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, a prodrug of aprepitant, can lower INR in patients on warfarin, which may reduce anticoagulation and raise clot risk. The change usually appears several days after a chemotherapy cycle.
How serious is the interaction between Fosaprepitant and Warfarin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check INR in the two weeks after each fosaprepitant dose, especially at days 7 to 10. Adjust warfarin as needed.
What other medicines interact with Warfarin?
MediHelp also lists interactions of Warfarin with, for example, Defibrotide, Ketorolac, Abciximab. The full list is on the Warfarin page.
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