procainamide

Procainamide is an injectable antiarrhythmic drug that is used to correct disturbances in the heart's rhythm. 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.

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

GENERIC AVAILABLE: Yes

Yes

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 test (CBC) 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.

An intravenous dose of 15 to 18 mg/kg may be administered over 25-30 minutes to adults. The initial dose is followed with a maintenance dose of 1-4 mg/min. Dose adjustments (reductions) are recommended in patients with liver and renal problems.

It can also be given by intramuscular (IM) injection. The IM dose is 0.5 to 1 g every 4 to 8 hours.

Dosing in children is based on both their age and weight. Infants usually need a loading dose. Depending on age and weight, a loading dose of the drug may be recommended; in addition, IV or IM dosing may be used. Pediatric specialists, or in an emergency, an Emergency Medicine physician should calculate the dose and route of administration.

: 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 anti-arrhythmics can result in additive or antagonistic effects on the heart.

Procainamide is secreted in breast milk. Mothers should discontinue nursing while taking procainamide.

What preparations of procainamide are available?

Injection: 100 and 500 mg/ml.

How should I keep procainamide stored?

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 C to 8 C (35 F to 46 F).