Drug interactions
Cimetidine + Procainamide
Severity: Major
Cimetidine and Procainamide: 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
Cimetidine reduces renal tubular secretion of procainamide and its metabolite NAPA, raising their concentrations. This can cause QT prolongation, arrhythmia, hypotension, and lupus-like effects.
What this interaction means in plain words
Cimetidine and Procainamide 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.
Why it happens
Competition for renal tubular cation transport (OCT2/MATE) reduces procainamide and NAPA clearance.
What to do
Prefer famotidine or another acid suppressant. If combined, monitor ECG and procainamide/NAPA levels and reduce the procainamide dose as needed.
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
Other interactions of Cimetidine
- Cimetidine + Dofetilide Contraindicated
- Cimetidine + Fezolinetant Contraindicated
- Alfentanil + Cimetidine Major
- Atazanavir + Cimetidine Major
- Carmustine + Cimetidine Major
- Cimetidine + Citalopram Major
Frequently asked questions
Can I take Cimetidine with Procainamide?
MediHelp rates the interaction as major. Cimetidine and Procainamide 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. Cimetidine reduces renal tubular secretion of procainamide and its metabolite NAPA, raising their concentrations. This can cause QT prolongation, arrhythmia, hypotension, and lupus-like effects.
How serious is the interaction between Cimetidine and Procainamide?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Prefer famotidine or another acid suppressant. If combined, monitor ECG and procainamide/NAPA levels and reduce the procainamide dose as needed.
What other medicines interact with Cimetidine?
MediHelp also lists interactions of Cimetidine with, for example, Dofetilide, Fezolinetant, Alfentanil. The full list is on the Cimetidine page.
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