Drug interactions
Idelalisib + Siponimod
Severity: Major
Idelalisib 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
Idelalisib is a strong CYP3A4 inhibitor and can raise siponimod exposure. Because CYP2C9 is the other main clearance route, the effect is larger when CYP2C9 activity is reduced. Increased exposure raises the risk of bradyarrhythmia and infection.
What this interaction means in plain words
Idelalisib 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.
Idelalisib belongs to Oncology; Siponimod belongs to Central Nervous System.
Why it happens
Strong CYP3A4 inhibition reduces siponimod clearance.
What to do
Avoid the combination in patients with CYP2C9*2/*3 or *3/*3 genotypes or on CYP2C9 inhibitors. Otherwise monitor heart rate, lymphocyte counts and infection signs.
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
Other interactions of Idelalisib
- Alfuzosin + Idelalisib Contraindicated
- Cisapride + Idelalisib Contraindicated
- Dihydroergotamine + Idelalisib Contraindicated
- Dronedarone + Idelalisib Contraindicated
- Eletriptan + Idelalisib Contraindicated
- Eplerenone + Idelalisib Contraindicated
Frequently asked questions
Can I take Idelalisib with Siponimod?
MediHelp rates the interaction as major. Idelalisib 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. Idelalisib is a strong CYP3A4 inhibitor and can raise siponimod exposure. Because CYP2C9 is the other main clearance route, the effect is larger when CYP2C9 activity is reduced. Increased exposure raises the risk of bradyarrhythmia and infection.
How serious is the interaction between Idelalisib 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 the combination in patients with CYP2C9*2/*3 or *3/*3 genotypes or on CYP2C9 inhibitors. Otherwise monitor heart rate, lymphocyte counts and infection signs.
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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