Drug interactions
Diltiazem + Propafenone
Severity: Major
Diltiazem and Propafenone: major interaction.
Last updated Sources: UK SmPC
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
Diltiazem can increase propafenone exposure and both have negative inotropic and conduction effects. This raises the risk of bradycardia, AV block, hypotension and proarrhythmia.
What this interaction means in plain words
Diltiazem and Propafenone 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; Propafenone belongs to Cardiovascular.
Why it happens
CYP3A4 inhibition raises propafenone concentrations, with additive pharmacodynamic conduction depression.
What to do
Monitor ECG for PR and QRS prolongation and watch heart rate and blood pressure. Reduce the propafenone dose or choose an alternative if conduction effects appear.
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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References
- ADIZEM-SR capsules 120 mg - SmPC sections 4.3/4.5 (class statement: other antiarrhythmic agents; "Since diltiazem has antiarrhythmic properties, its concomitant prescription with other antiarrhythmic agents is not recommended (additive risk of increased card") — electronic medicines compendium (UK SmPC)
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 Propafenone
- Dofetilide + Propafenone Contraindicated
- Dronedarone + Propafenone Contraindicated
- Nilotinib + Propafenone Contraindicated
- Nirmatrelvir / ritonavir + Propafenone Contraindicated
- Nirmatrelvir + Propafenone Contraindicated
- Pimozide + Propafenone Contraindicated
Frequently asked questions
Can I take Diltiazem with Propafenone?
MediHelp rates the interaction as major. Diltiazem and Propafenone 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 can increase propafenone exposure and both have negative inotropic and conduction effects. This raises the risk of bradycardia, AV block, hypotension and proarrhythmia.
How serious is the interaction between Diltiazem and Propafenone?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor ECG for PR and QRS prolongation and watch heart rate and blood pressure. Reduce the propafenone dose or choose an alternative if conduction effects appear.
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.
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