Drug interactions
Fluorouracil + Siponimod
Severity: Moderate
Fluorouracil and Siponimod: 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
Fluorouracil has been reported to inhibit CYP2C9 and may therefore increase exposure to siponimod, which is mainly cleared by this enzyme. Siponimod is also immunosuppressive, so lymphopenia could add to the myelosuppression caused by chemotherapy.
What this interaction means in plain words
Fluorouracil and Siponimod 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.
Fluorouracil belongs to Oncology; Siponimod belongs to Central Nervous System.
Why it happens
Fluorouracil may inhibit CYP2C9, and both drugs reduce lymphocyte counts.
What to do
Monitor blood counts, including lymphocytes, and watch for infections and siponimod adverse effects. Consider interrupting siponimod during myelosuppressive chemotherapy.
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 Siponimod
- Cladribine + Siponimod Contraindicated
- Fingolimod + Siponimod Contraindicated
- Fluconazole + Siponimod Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Siponimod Contraindicated
- Ponesimod + Siponimod Contraindicated
- Siponimod + Thioridazine Contraindicated
Other interactions of Fluorouracil
Frequently asked questions
Can I take Fluorouracil with Siponimod?
MediHelp rates the interaction as moderate. Fluorouracil and Siponimod 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. Fluorouracil has been reported to inhibit CYP2C9 and may therefore increase exposure to siponimod, which is mainly cleared by this enzyme. Siponimod is also immunosuppressive, so lymphopenia could add to the myelosuppression caused by chemotherapy.
How serious is the interaction between Fluorouracil and Siponimod?
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 blood counts, including lymphocytes, and watch for infections and siponimod adverse effects. Consider interrupting siponimod during myelosuppressive chemotherapy.
What other medicines interact with Siponimod?
MediHelp also lists interactions of Siponimod with, for example, Cladribine, Fingolimod, Fluconazole. The full list is on the Siponimod page.
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