Drug interactions
Phenobarbital + Siponimod
Severity: Major
Phenobarbital and Siponimod: major 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
Phenobarbital is an inducer of CYP enzymes and may substantially lower siponimod exposure, risking loss of disease control. The risk is higher in patients with reduced CYP2C9 function.
What this interaction means in plain words
Phenobarbital and Siponimod can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Induction of CYP3A4 and CYP2C9 increases siponimod clearance.
What to do
Avoid in patients with CYP2C9*1/*3 or *2/*3 genotypes and consider an alternative anticonvulsant. Otherwise monitor clinical response.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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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 Phenobarbital with Siponimod?
MediHelp rates the interaction as major. Phenobarbital and Siponimod can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Phenobarbital is an inducer of CYP enzymes and may substantially lower siponimod exposure, risking loss of disease control. The risk is higher in patients with reduced CYP2C9 function.
How serious is the interaction between Phenobarbital and Siponimod?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid in patients with CYP2C9*1/*3 or *2/*3 genotypes and consider an alternative anticonvulsant. Otherwise monitor clinical response.
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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