Procainamide Hydrochloride

Pronunciation: pro-CANE-uh-mide HIGH-droe-KLOR-ide
Class: Antiarrhythmic agent

Trade Names

Procainamide Hydrochloride
- Injection 100 mg/mL
- Injection 500 mg/mL

Pharmacology

Increases effective refractory period of atria and bundle of His-Purkinje system; reduces impulse conduction velocity and myocardial excitability in atria, Purkinje fibers, and ventricles.

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Pharmacokinetics

Absorption

Rapid absorption (IM), immediate absorption (IV).

Distribution

Protein binding is 15% to 20%, also bound to tissues of the heart, liver, lung, and kidney. Vd is 2 L/kg. The drug distributes into breast milk (procainamide and N-acetylprocainamide [NAPA]).

Metabolism

Metabolized in liver to NAPA, an active metabolite exerting significant antiarrhythmic activity. Approximately 25% of dose converted to NAPA, up to 40% conversion occurs in patients who are rapid acetylators.

Elimination

The half-life is 3 to 4 h (healthy renal function, procainamide) and approximately 6 h (NAPA). Urinary excretion (6% to 52% NAPA, 30% to 60% as unchanged procainamide); a trace amount is excreted in urine as free and conjugated p-aminobenzoic acid.

Peak

15 to 60 min (IM), and immediate (IV).

Special Populations

Elimination half-life is prolonged.

Elimination half-life is prolonged.

In infants, half-life and renal Cl are reduced.

Indications and Usage

Treatment of documented ventricular arrhythmias that are life threatening.

Contraindications

Complete heart block; idiosyncratic hypersensitivity; lupus erythematosus; torsades de pointes.

Dosage and Administration

IV 20 mg/min for 25 to 30 min as loading dose, then 2 to 6 mg/min for maintenance.

IM 50 mg/kg/day in divided doses every 3 to 6 h until oral therapy is possible.

General Advice

• Prepare IV infusion solution using D5W. Use controlled infusion device.
• IV solutions may turn slightly yellow or light amber on standing, but potency is not affected.
• For direct IV injection, do not exceed max IV rate of 50 mg/min and do not give more than 100 mg in any 5-min period.
• Wait 3 to 4 h after last IV dose before first oral dose.

Storage/Stability

Store between 59° and 86°F for 24 h or for 7 days if refrigerated. Discard IV infusion solutions that are darker than light amber.

Drug Interactions

May increase procainamide and NAPA concentrations.

May increase the risk of life-threatening cardiac arrhythmias, including torsades de pointes.

Coadministration with procainamide is contraindicated.

Adverse Reactions

Cardiovascular

Proarrhythmic effects; hypotension.

CNS

Dizziness; weakness; depression; psychosis with hallucinations.

Dermatologic

Angioneurotic edema; urticaria; pruritus; flushing; rash.

EENT

Bitter taste.

GI

Nausea; vomiting; anorexia; abdominal pain.

Hematologic

Neutropenia; thrombocytopenia; hemolytic anemia; agranulocytosis.

Miscellaneous

Lupus erythematosus-like syndrome.

Precautions

Pregnancy

Category C .

Lactation

Excreted in breast milk.

Children

Safety and efficacy not established.

Hypersensitivity

Consider the possibility of cross-sensitivity to procainamide in patients sensitive to procaine or other ester-type local anesthetics.

Renal Function

Individual dose adjustment may be necessary.

Special Risk Patients

Elderly patients and patients with renal, hepatic, or cardiac function impairment will require smaller or less frequent doses. Individual dosage adjustment will be necessary.

Sulfite Sensitivity

Parenteral forms contain sulfites.

Asymptomatic PVCs

Avoid use of product in treatment of patients with this condition.

Blood dyscrasias

Agranulocytosis, bone marrow depression, neutropenia, hypoplastic anemia, and thrombocytopenia have been reported; monitor carefully.

Complete heart block

Do not administer to patients with complete heart block because of effects in suppressing nodal or ventricular pacemakers and hazard of asystole.

Concurrent antiarrhythmic agents

May see enhanced prolongation of conduction or depression of contractility and hypotension.

Digitalis intoxication

Use with caution treating arrhythmias associated with digitalis intoxication.

First-degree heart block

Use with caution if first-degree heart block develops during procainamide therapy.

Myasthenia gravis

Patients may experience increase of muscle weakness. Observe closely.

Predigitalization for atrial flutter or fibrillation

Cardiovert or digitalize patient prior to procainamide therapy to avoid enhancement of AV conduction.

Overdosage

Symptoms

Hypotension, widening of QRS complex, prolonged QT and PR intervals, ventricular tachyarrhythmias.

Patient Information

• Explain importance of informing other health care providers or dentists about therapy before surgical or dental procedures.
• Emphasize importance of drug compliance. Caution patient not to make up for missed doses.
• Instruct patient to report the following symptoms to health care provider immediately: difficulty breathing, pounding or irregular heartbeat, joint pain, fever, chills, skin rash, continued dizziness.
• Explain that diarrhea, nausea, dizziness, or loss of appetite may occur and to contact health care provider if symptoms are bothersome.
• Advise patient that drug may cause dizziness and to use caution when driving or performing other tasks requiring mental alertness.

Copyright © 2009 Wolters Kluwer Health.