Procainamide

General

• Type: Class Ia Antiarrhythmic
• Dosage Forms: 100 mg/mL (10 mL); 500 mg/mL (2 mL)
• Common Trade Names: Apo-Procainamide; Procainamide Hydrochloride Injection

Adult Dosing

Arrythmia

• Considered Drug of Choice for stable Wide-Complex Tachycardia Class IIa reccomendation
• 17 mg/kg at a rate of 20 - 50 mg/min; intravenously over 25 - 30 minutes
• Give until:
  • arrhythmia is suppressed
  • patient develops hypotension
  • QRS segment prolongs by >50% of baseline
  • total of 17 mg/kg is given; max 1 gram
• If effective, start continuous infusion at 1-4 mg/min
  • Continuous infusion has fewer adverse effects than bolus

Special Populations

• Pregnancy Rating:
• Lactation risk:
• Renal Dosing
  • Adult
  • Pediatric
• Hepatic Dosing
  • Adult
  • Pediatric

Indications

• Wide-complex tachycardia of unknown type (in patient with preserved left ventricular function)
• Stable ventricular tachycardia

Contraindications

• Allergy to class/drug
• Not recommended for ventricular fibrillation or pulseless ventricular tachycardia, as it takes too long to dose
• 2nd or 3rd atrioventricular block
• Severe glycoside intoxication
• Prolonged QT segment
• Myasthenia gravis

Adverse Reactions

• Myocardial depression
• Watch for QRS/QT segment prolongation, ventricular tachycardia, ventricular fibrillation, complete atrioventricular block, torsades de pointes

Pharmacology

• Half-life:
• Metabolism:
• Excretion:
• Kinetics: Onset of action 5 - 10 minutes

Mechanism of Action

• Class Ia
  • Binds to fast sodium channels in inactive state inhibiting recovery after repolarization
  • Prolongs action potential and reduces speed of impulse conduction
    • Depresses myocardial conduction
  • May act as negative inotrope, causing hypotension through peripheral vasodilation

See Also

• Antiarrhythmics