Procainamide and Quinidine interaction
Procainamide and Quinidine: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Procainamide (Procainamide Hydrochloride) label · effective 2026-08-31
Considering the known proarrhythmic properties of procainamide and the lack of evidence of improved survival for any antiarrhythmic drug in patients without life-threatening arrhythmias, the use of procainamide as well as other antiarrhythmic agents should be reserved for patients with life-threatening ventricular arrhythmias.
Anticholinergic drugs administered concurrently with PA may produce additive antivagal effects on A-V nodal conduction, although this is not as well documented for PA as for quinidine.
Concurrent Other Antiarrhythmic Agents Concurrent use of PA with other Group 1A antiarrhythmic agents such as quinidine or disopyramide may produce enhanced prolongation of conduction or depression of contractility and hypotension, especially in patients with cardiac decompensation.
Drug Interactions If other antiarrhythmic drugs are being used, additive effects on the heart may occur with PA administration, and dosage reduction may be necessary (see WARNINGS ).
From the Quinidine (Quinidine Gluconate) label · effective 2024-08-27
Proarrhythmic effects Like many other drugs (including all other Class Ia antiarrhythmics), quinidine prolongs the QT c interval, and this can lead to torsades de pointes , a life-threatening ventricular arrhythmia (see OVERDOSAGE ).
Perhaps by competing for pathways of renal clearance, coadministration of quinidine causes an increase in serum levels of procainamide .
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.