GENERIC NAME: procainamide
　

BRAND NAME: Pronestyl; Procan-SR; Procanbid
DRUG CLASS AND MECHANISM: Procainamide is a cardiac antiarrhythmic medication used to correct disturbances in the heart's rhythm. Three actions are responsible for procainamide's ability to stop heart rhythm disturbances (arrhythmias) and prevent their recurrence. Procainamide decreases the speed of electrical conduction in the heart muscle; it prolongs the electrical phase during which heart muscle cells can be electrically stimulated (develop an action potential) ; it prolongs the recovery period during which the heart muscle cells cannot be stimulated (the refractory period). Procainamide was approved for use in the United States in 1950. A twice-a-day formulation, Procanbid, was approved in January, 1996.

PRESCRIPTION: yes

GENERIC AVAILABLE: yes

PREPARATIONS: Sustained release tablets for four times a day administration: 250mg, 500mg, 750mg,1000mg. Sustained release tablets for twice daily administration: 500mg, 1000mg. Immediate-release tablets and capsules: 250mg, 500mg, 750mg.

STORAGE: Tablets and capsules should be kept at room temperature, between 15?and 30癈 (59-86癋).

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 AV junction as well as extra pathways (bypass tracts) between the atria and ventricles;
·Intermittent atrial fibrillation and flutter;
·Sinus rhythm after conversion from atrial fibrillation or flutter to prevent recurrence; and
·Ventricular tachycardia.
DOSING: Procainamide is given every four hours, or two, three, or four times per day, depending on the specific formulation prescribed.

DRUG INTERACTIONS: Amiodarone (Cordarone) increases the blood concentrations of procainamide by either decreasing the kidney's ability to clear procainamide or by decreasing the ability of the liver to metabolize procainamide. Cimetidine (Tagamet) and trimethoprim (one of the ingredients in Bactrim or Septra) inhibit the kidney's ability to eliminate procainamide. As a result, blood concentrations of procainamide may increase and cause toxicity.

Concurrent administration of procainamide with other antiarrhythmics can result in additive or antagonistic effects on the heart.

PREGNANCY: Procainamide crosses the placenta. Well- controlled studies have not been performed in humans. Therefore procainamide should be avoided in pregnant patients unless the physician feels that the potential benefits outweigh the unknown risks.

NURSING MOTHERS: Procainamide should be used with caution during breast-feeding. Procainamide is excreted into breast milk.

SIDE EFFECTS: 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 of the drug.

Rarely, procainamide can cause confusion, hallucinations, and depression