Drug interactions
Diltiazem + Siponimod
Severity: Major
Diltiazem and Siponimod: major interaction.
Last updated Sources: US FDA label
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 lowers heart rate at initiation, and diltiazem adds to bradycardia and AV conduction slowing. Diltiazem, a moderate CYP3A4 inhibitor, may also modestly raise siponimod exposure, particularly in CYP2C9 poor-metabolizer genotypes.
What this interaction means in plain words
Diltiazem 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.
Diltiazem belongs to Cardiovascular; Siponimod belongs to Central Nervous System.
Why it happens
Additive heart rate slowing plus CYP3A4 inhibition reducing siponimod clearance.
What to do
Avoid starting siponimod in patients on diltiazem unless cardiology advises; if used, monitor heart rate and ECG on initiation. Avoid the combination in patients with CYP2C9*3/*3 genotype or reduced CYP2C9 activity.
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 Diltiazem 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.
References
Other interactions of Diltiazem
- Diltiazem + Flibanserin Contraindicated
- Diltiazem + Ivabradine Contraindicated
- Diltiazem + Lomitapide Contraindicated
- Diltiazem + Lonafarnib Contraindicated
- Acebutolol + Diltiazem Major
- Alfentanil + Diltiazem Major
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 Diltiazem with Siponimod?
MediHelp rates the interaction as major. Diltiazem 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 lowers heart rate at initiation, and diltiazem adds to bradycardia and AV conduction slowing. Diltiazem, a moderate CYP3A4 inhibitor, may also modestly raise siponimod exposure, particularly in CYP2C9 poor-metabolizer genotypes.
How serious is the interaction between Diltiazem 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 starting siponimod in patients on diltiazem unless cardiology advises; if used, monitor heart rate and ECG on initiation. Avoid the combination in patients with CYP2C9*3/*3 genotype or reduced CYP2C9 activity.
What other medicines interact with Diltiazem?
MediHelp also lists interactions of Diltiazem with, for example, Flibanserin, Ivabradine, Lomitapide. The full list is on the Diltiazem 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.
