Drug interactions
Ritonavir + Siponimod
Severity: Major
Ritonavir 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
Ritonavir is a strong CYP3A4 inhibitor and increases siponimod exposure. This increases the risk of bradyarrhythmia and lymphopenia, particularly in patients with reduced CYP2C9 activity.
What this interaction means in plain words
Ritonavir 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.
Ritonavir belongs to Anti Virals; Siponimod belongs to Central Nervous System.
Why it happens
Inhibition of CYP3A4 reduces siponimod clearance.
What to do
Avoid the combination where possible. If used, monitor heart rate, ECG and lymphocyte count; avoid in CYP2C9*3 carriers.
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 Ritonavir
- Alfuzosin + Ritonavir Contraindicated
- Amiodarone + Ritonavir Contraindicated
- Avanafil + Ritonavir Contraindicated
- Colchicine + Ritonavir Contraindicated
- Dronedarone + Ritonavir Contraindicated
- Eletriptan + Ritonavir Contraindicated
Frequently asked questions
Can I take Ritonavir with Siponimod?
MediHelp rates the interaction as major. Ritonavir 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. Ritonavir is a strong CYP3A4 inhibitor and increases siponimod exposure. This increases the risk of bradyarrhythmia and lymphopenia, particularly in patients with reduced CYP2C9 activity.
How serious is the interaction between Ritonavir 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 where possible. If used, monitor heart rate, ECG and lymphocyte count; avoid in CYP2C9*3 carriers.
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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