Drug interactions
Fostamatinib + Leflunomide
Severity: Moderate
Fostamatinib and Leflunomide: 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
Fostamatinib's active metabolite R406 inhibits BCRP, and teriflunomide from leflunomide is a BCRP substrate. Exposure to teriflunomide may increase, raising the risk of hepatotoxicity, myelosuppression and other adverse effects.
What this interaction means in plain words
Fostamatinib and Leflunomide 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.
Fostamatinib belongs to Oncology; Leflunomide belongs to Musculoskeletal.
Why it happens
R406 inhibits BCRP-mediated efflux, increasing teriflunomide exposure.
What to do
Monitor liver enzymes and blood counts, and watch for leflunomide adverse effects. Consider reducing the leflunomide dose if toxicity appears.
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 Leflunomide
- Bcg vaccine live + Leflunomide Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Leflunomide Contraindicated
- Leflunomide + Measles mumps and rubella vaccine live Contraindicated
- Leflunomide + Measles mumps rubella and varicella vaccine live Contraindicated
- Leflunomide + Measles vaccine Contraindicated
- Leflunomide + Smallpox vaccine live Contraindicated
Other interactions of Fostamatinib
- Colchicine + Fostamatinib Major
- Fostamatinib + Phenytoin Major
- Amobarbital + Fostamatinib Moderate
- Apalutamide + Fostamatinib Moderate
- Atorvastatin + Fostamatinib Moderate
- Bosentan + Fostamatinib Moderate
Frequently asked questions
Can I take Fostamatinib with Leflunomide?
MediHelp rates the interaction as moderate. Fostamatinib and Leflunomide 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. Fostamatinib's active metabolite R406 inhibits BCRP, and teriflunomide from leflunomide is a BCRP substrate. Exposure to teriflunomide may increase, raising the risk of hepatotoxicity, myelosuppression and other adverse effects.
How serious is the interaction between Fostamatinib and Leflunomide?
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 liver enzymes and blood counts, and watch for leflunomide adverse effects. Consider reducing the leflunomide dose if toxicity appears.
What other medicines interact with Leflunomide?
MediHelp also lists interactions of Leflunomide with, for example, Bcg vaccine live, Influenza virus vaccine quadrivalent intranasal, Measles mumps and rubella vaccine live. The full list is on the Leflunomide page.
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