Procainamide

General

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

Adult Dosing

Arrythmia

Drug of Choice for stable wide complex tachycardia (Class IIa recommendation)

  • 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

Pediatric Dosing

Arrythmia

  • Stable wide-complex tachycardia or SVT
  • 15mg/kg infused over 30-60 minutes
    • Stop infusion if hypotension occurs or QRS complex widens by >50% of baseline

Special Populations

  • Pregnancy Rating: Class C
  • Lactation risk: Procainamide and its metabolite are found in breast milk. Due to the potential for adverse events in the nursing infant, breast-feeding is not recommended by the manufacturer.
  • Renal Dosing
    • Adult: Drip rate is 1-2 mg/min for renal/cardiac failure
    • 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:
    • Children: 1.7 hours
    • Adults with normal renal function: 2.5-4.7 hours
  • Metabolism: By acetylation in the liver to produce N-acetyl procainamide (NAPA)
  • Excretion: Urinary excretion (25% as NAPA)
  • Kinetics: Onset of action 5 - 10 minutes

Mechanism of Action

IPad image 2015-5-25-1435238186649 0.jpg
  • 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

Comments

See Also

References