Drug interactions
Siponimod + Sulfamethoxazole
Severity: Moderate
Siponimod and Sulfamethoxazole: 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
Sulfamethoxazole inhibits CYP2C9 and may raise siponimod exposure. The effect is greater in patients with reduced CYP2C9 function or on a CYP3A4 inhibitor.
What this interaction means in plain words
Siponimod and Sulfamethoxazole 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
Moderate inhibition of CYP2C9 reduces siponimod clearance.
What to do
Monitor heart rate and adverse effects. Avoid in patients who also take a CYP3A4 inhibitor, or choose a different antibiotic.
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
Frequently asked questions
Can I take Siponimod with Sulfamethoxazole?
MediHelp rates the interaction as moderate. Siponimod and Sulfamethoxazole 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. Sulfamethoxazole inhibits CYP2C9 and may raise siponimod exposure. The effect is greater in patients with reduced CYP2C9 function or on a CYP3A4 inhibitor.
How serious is the interaction between Siponimod and Sulfamethoxazole?
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 heart rate and adverse effects. Avoid in patients who also take a CYP3A4 inhibitor, or choose a different antibiotic.
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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