Drug interactions
Atazanavir + Siponimod
Severity: Major
Atazanavir 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
Siponimod is cleared mainly by CYP2C9, with a smaller contribution from CYP3A4. Atazanavir inhibits CYP3A4 and may increase siponimod exposure, and the increase is greater in patients with reduced CYP2C9 activity. Higher exposure raises the risk of bradyarrhythmia, lymphopenia, and other adverse effects.
What this interaction means in plain words
Atazanavir 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.
Atazanavir belongs to Anti Virals; Siponimod belongs to Central Nervous System.
Why it happens
Inhibition of CYP3A4 by atazanavir reduces siponimod clearance, an effect amplified when CYP2C9 metabolism is also reduced.
What to do
Avoid siponimod with combined moderate or strong CYP3A4 and CYP2C9 inhibition, and check the patient's CYP2C9 genotype. Monitor heart rate, lymphocyte counts, and adverse effects if the combination is used.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Atazanavir and Siponimod, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
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 Atazanavir
- Alfuzosin + Atazanavir Contraindicated
- Atazanavir + Avanafil Contraindicated
- Atazanavir + Dronedarone Contraindicated
- Atazanavir + Eletriptan Contraindicated
- Atazanavir + Eplerenone Contraindicated
- Atazanavir + Ergotamine Contraindicated
Frequently asked questions
Can I take Atazanavir with Siponimod?
MediHelp rates the interaction as major. Atazanavir 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. Siponimod is cleared mainly by CYP2C9, with a smaller contribution from CYP3A4. Atazanavir inhibits CYP3A4 and may increase siponimod exposure, and the increase is greater in patients with reduced CYP2C9 activity. Higher exposure raises the risk of bradyarrhythmia, lymphopenia, and other adverse effects.
How serious is the interaction between Atazanavir 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 siponimod with combined moderate or strong CYP3A4 and CYP2C9 inhibition, and check the patient's CYP2C9 genotype. Monitor heart rate, lymphocyte counts, and adverse effects if the combination is used.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
