Drug interactions
Grapefruit + Siponimod
Severity: Moderate
Grapefruit 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
Grapefruit juice inhibits intestinal CYP3A4 and may modestly increase siponimod exposure. The effect is unlikely to be large in patients with normal CYP2C9 function, but it may matter in those with reduced CYP2C9 activity. Higher exposure raises the risk of bradycardia and immunosuppression.
What this interaction means in plain words
Grapefruit 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.
Why it happens
Grapefruit components inhibit intestinal CYP3A4, reducing first-pass metabolism of siponimod.
What to do
Advise patients with CYP2C9*2/*3 or *3/*3 genotypes, or on CYP2C9 inhibitors, to avoid grapefruit products. Others should keep intake consistent and be monitored for bradycardia.
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 Grapefruit with Siponimod?
MediHelp rates the interaction as moderate. Grapefruit 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. Grapefruit juice inhibits intestinal CYP3A4 and may modestly increase siponimod exposure. The effect is unlikely to be large in patients with normal CYP2C9 function, but it may matter in those with reduced CYP2C9 activity. Higher exposure raises the risk of bradycardia and immunosuppression.
How serious is the interaction between Grapefruit 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: Advise patients with CYP2C9*2/*3 or *3/*3 genotypes, or on CYP2C9 inhibitors, to avoid grapefruit products. Others should keep intake consistent and be monitored for bradycardia.
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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