Procainamide (patient information)

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]

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Overview

Procainamide Information for Patients

Generic Name: Procainamide hydrochloride Dosage Form: capsules

The physician is advised to explain to the patient that close cooperation in adhering to the prescribed dosage schedule is of great importance in controlling the cardiac arrhythmia safely. The patient should understand clearly that more medication is not necessarily better and may be dangerous, that skipping doses or increasing intervals between doses to suit personal convenience may lead to loss of control of the heart problem, and that “making up” missed doses by doubling up later may be hazardous.

The patient should be encouraged to disclose any past history of drug sensitivity, especially to procaine or other local anesthetic agents, or aspirin, and to report any history of kidney disease, congestive heart failure, myasthenia gravis, liver disease, or lupus erythematosus.

The patient should be counseled to report promptly any symptoms of arthralgia, myalgia, fever, chills, skin rash, easy bruising, sore throat or sore mouth, infections, dark urine or icterus, wheezing, muscular weakness, chest or abdominal pain, palpitations, nausea, vomiting, anorexia, diarrhea, hallucinations, dizziness or depression.

Laboratory Tests

Laboratory tests such as complete blood count (CBC), electrocardiogram, and serum creatinine or urea nitrogen may be indicated, depending on the clinical situation, and periodic rechecking of the CBC and ANA may be helpful in early detection of untoward reactions.

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).

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.

Patients taking PA who require neuromuscular blocking agents such as succinylcholine may require less than usual doses of the latter, due to PA effects on reducing acetylcholine release.

Drug/Laboratory Test Interactions

Suprapharmacologic concentrations of lidocaine and meprobamate may inhibit fluorescence of PA and NAPA, and propranolol shows a native fluorescence close to the PA/NAPA peak wavelengths, so that tests which depend on fluorescence measurement may be affected.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Long term studies in animals have not been performed.

Pregnancy

Teratogenic Effects

Pregnancy Category C

Animal reproduction studies have not been conducted with PA. It also is not known whether PA can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. PA should be given to a pregnant woman only if clearly needed.

Nursing Mothers

Both PA and NAPA are excreted in human milk, and absorbed by the nursing infant. Because of the potential for serious adverse reactions in nursing infants, a decision to discontinue nursing or the drug should be made, taking into account the importance of the drug to the mother.

Pediatric Use

Safety and effectiveness in pediatric patients have not been established.

Adverse Reactions

Cardiovascular System

Hypotension following oral PA administration is rare. Hypotension and serious disturbances of cardiorhythm such as ventricular asystole or fibrillation are more common after intravenous administration (see OVERDOSAGE and WARNINGS). Second degree heart block has been reported in 2 of almost 500 patients taking PA orally.

Multisystem

A lupus erythematosus-like syndrome of arthralgia, pleural or abdominal pain, and sometimes arthritis, pleural effusion, pericarditis, fever, chills, myalgia, and possibly related hematologic or skin lesions (see below) is fairly common after prolonged PA administration, perhaps more often in patients who are slow acetylators (see Boxed Warning and PRECAUTIONS). While some series have reported less than 1 in 500, others have reported the syndrome in up to 30 percent of patients on long term oral PA therapy. If discontinuation of PA does not reverse the lupoid symptoms, corticosteroid treatment may be effective.

Hematologic

Neutropenia, thrombocytopenia, or hemolytic anemia may rarely be encountered. Agranulocytosis has occurred after repeated use of PA, and deaths have been reported (see Boxed Warning, WARNINGS section).

Skin

Angioneurotic edema, urticaria, pruritus, flushing, and maculopapular rash have also occurred occasionally (see Boxed WARNING).

Gastrointestinal

Anorexia, nausea, vomiting, abdominal pain, bitter taste, or diarrhea may occur in 3 to 4 percent of patients taking oral Procainamide.

Elevated Liver Enzymes

Elevations of transaminase with and without elevations of alkaline phosphatase and bilirubin have been reported. Some patients have had clinical symptoms (e.g., malaise, right upper quadrant pain). Deaths from liver failure have been reported.

Nervous System

Dizziness or giddiness, weakness, mental depression, and psychosis with hallucinations have been reported occasionally.

Overdosage

Progressive widening of the QRS complex, prolonged Q-T and P-R intervals, lowering of the R and T waves, as well as increasing A-V block, may be seen with doses which are excessive for a given patient. Increased ventricular extrasystoles, or even ventricular tachycardia or fibrillation may occur. After intravenous administration but seldom after oral therapy, transient high plasma levels of PA may induce hypotension, affecting systolic more than diastolic pressures especially in hypertensive patients. Such high levels may also produce central nervous depression, tremor, and even respiratory depression.

Plasma levels above 10 µg/mL are increasingly associated with toxic findings which are seen occasionally in the 10 to 12 µg/mL range, more often in the 12 to 15 µg/mL range, and commonly in patients with plasma levels greater than 15 µg/mL. A single oral dose of 2 g may produce overdosage symptoms, while 3 g may be dangerous, especially if the patient is a slow acetylator, has decreased renal function, or underlying organic heart disease.

Treatment of overdosage or toxic manifestations includes general supportive measures, close observation, monitoring of vital signs and possibly intravenous pressor agents and mechanical cardiorespiratory support. If available, PA and NAPA plasma levels may be helpful in assessing the potential degree of toxicity and response to therapy. Both PA and NAPA are removed from the circulation by hemodialysis but not peritoneal dialysis. No specific antidote for PA is known.

Procainamide Dosage and Administration

The oral dose and interval of administration should be adjusted for the individual patient, based on clinical assessment of the degree of underlying myocardial disease, the patient’s age, and renal function.

As a general guide, for younger patients with normal renal function, an initial total daily oral dose of up to 50 mg/kg of body weight of Procainamide Hydrochloride Capsules may be used, given in divided doses, every three hours, to maintain therapeutic blood levels. For older patients, especially those over 50 years of age, or for patients with renal, hepatic, or cardiac insufficiency, lesser amounts or longer intervals may produce adequate blood levels. The initial total daily dose should be divided for administration at three, four, or six hour intervals as estimated for the patient’s needs; then, the dose and interval should be adjusted for the individual. To provide up to 50 mg per kg of body weight per day:*

• Initial dosage schedule guide only, to be adjusted for each patient individually, based on age, cardiorenal function, blood level (if available), and clinical response.

Patients weighing:

• 88-110 lb (40-50 kg) 250 mg q3h to 500 mg q6h
• 132-154 lb (60-70 kg) 375 mg q3h to 750 mg q6h
• 176-198 lb (80-90 kg) 500 mg q3h to 1 g q6h
• >220 lb ( > 100 kg) 625 mg q3h to 1.25 g q6h

How is Procainamide Supplied

Available as yellow capsules, imprinted 2345, containing 250 mg of Procainamide Hydrochloride USP; as orange and white capsules, imprinted 2346, containing 375 mg of Procainamide Hydrochloride USP; and as orange and yellow capsules, imprinted 2347, containing 500 mg of Procainamide Hydrochloride USP. All strengths are packaged in bottles of 100, 250 and 1000 capsules.

PHARMACIST: Dispense in a tight container as defined in the USP. Use child-resistant closure (as required).

Store at controlled room temperature 15°-30°C (59°-86°F) (See USP).

MANUFACTURED BY 0172

IVAX PHARMACEUTICALS, INC. 07/02

MIAMI, FL 33137 B14