What the FDA labels say about taking them together
Procainamide and quinidine
Procainamide's FDA label of February 17, 2025 names quinidine in its drug interactions section, and quinidine's label names procainamide too. The quinidine label: “Perhaps by competing for pathways of renal clearance, coadministration of quinidine causes an increase in serum levels of procainamide.”
Check it at the source: the procainamide FDA label on DailyMed (effective February 17, 2025, Caplin Steriles Limited); the quinidine FDA label on DailyMed (effective February 1, 2018, Sun Pharmaceutical Industries, Inc.).
What does the procainamide label say about quinidine?
Procainamide label, drug interactionsAnticholinergic 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.
Procainamide label, warningsConcurrent 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.
Source: FDA drug label (Procainamide Hydrochloride), Caplin Steriles Limited, effective February 17, 2025 (SPL set fcaa5e9a-3c8a-4796-aa87-626268b6cf60), via openFDA; the full label on DailyMed
What does the quinidine label say about procainamide?
Quinidine label, drug interactionsPerhaps by competing for pathways of renal clearance, coadministration of quinidine causes an increase in serum levels of procainamide.
Source: FDA drug label (Quinidine Gluconate), Sun Pharmaceutical Industries, Inc., effective February 1, 2018 (SPL set 5023f053-fcc4-4c2c-aa59-9ec198ad185e), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Procainamide | Quinidine | |
|---|---|---|
| Labeled for | n/a | Atrial fibrillation |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | n/a | $4.92 per tablet 324 mg tablet |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once