procainamide, Pronestyl; Procan-SR; Procanbid

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GENERIC NAME: procainamide

BRAND NAME: Pronestyl, Procan-SR, Procanbid (These brands no longer are available in the U.S.)

DRUG CLASS AND MECHANISM: Procainamide is an injectable drug that is used to correct disturbances in the heart's rhythm; it is an antiarrhythmic drug. Three actions are responsible for its ability to correct disturbances of rhythm and prevent their recurrence. Procainamide decreases the speed of electrical conduction through the heart muscle, prolongs the electrical phase during which the heart's muscle cells can be electrically stimulated, and prolongs the recovery period during which the heart muscle cells cannot be stimulated. Procainamide was approved for use by the FDA in 1950.



PREPARATIONS: Injection: 100 and 500 mg/ml.

STORAGE: Procainamide may be kept at room temperature. If diluted it is stable for 24 hours at room temperature or seven days if refrigerated at 2 to 8 C (35 to 46 F).

PRESCRIBED FOR: Procainamide is an antiarrhythmic drug used in the treatment of abnormal heart rhythms such as:

  • early (premature) atrial and ventricular beats;
  • intermittent rapid rhythms (tachycardias) involving the atria and atrio-ventricular (AV) junction as well as abnormal pathways (bypass tracts) between the atria and ventricles;
  • intermittent atrial fibrillation and flutter;
  • after conversion from atrial fibrillation or flutter to prevent recurrence; and
  • ventricular tachycardia.

DOSING: An intravenous dose of 500-600 mg over may be administered over 25-30 minutes to adults. The initial dose is followed with a maintenance dose of 1-6 mg/min.

DRUG INTERACTIONS: Amiodarone (Cordarone) increases the blood concentrations of procainamide by either decreasing the kidneys or the liver's abilities to remove procainamide. Combining procainamide with thioridazine (Mellaril), pimozide (Orap), quinolones for example, levofloxacin (Levaquin), tricyclic antidepressants for example, amitriptyline (Endep, Elavil), and ziprasidone (Geodon) may increase the risk of abnormal heart beats because these drugs may also prolong the recovery period of the heart. Concurrent administration of procainamide with other antiarrhythmics can result in additive or antagonistic effects on the heart.

PREGNANCY: Procainamide crosses the placenta. Adequate studies have not been performed in humans to determine if there are any effects of procainamide on the fetus. Therefore, procainamide should be avoided in pregnant patients unless the physician feels that the potential benefits outweigh the unknown risks.

NURSING MOTHERS: There are no adequate studies in nursing mothers. Available information suggests that there is minimal risk of adverse effects to the infant.

SIDE EFFECTS: Common reactions include diarrhea, nausea, vomiting, rash, low blood pressure, itching, flushing, and slow heart beat. Severe reactions include abnormal heart beats, seizures, heart arrest, and blood disorders. A severe reduction in white blood cell count occurs relatively rarely with procainamide therapy and is more common with the sustained-release preparations. This side effect has caused death. For this reason, patients on sustained-release procainamide get a complete blood count every 2 weeks for the first 3 months of treatment. A syndrome resembling lupus erythematosus, including fever, chills, joint pain, chest pain, and/or skin rash can occur with procainamide. The lupus-like syndrome is reversible after stopping the drug. Rarely, procainamide can cause confusion, hallucinations, and depression.

Reference: FDA Prescribing Information

Last Editorial Review: 9/10/2009

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