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)

• 100 mg IV x 2 min q5min as needed to max dose 17 mg/kg
• Give until:
  • Arrhythmia is suppressed
  • Patient develops hypotension
  • QRS segment prolongs by >50% of baseline
  • Total of 17 mg/kg given
• 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

• 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

Indications by Condition

The following table is automatically generated from disease/condition pages across WikEM.

Indication	Dose	Context	Route	Population
Atrial fibrillation (main)	1 g IV over 60 min (Ottawa protocol); hold if SBP <100	Rhythm control (Ottawa aggressive protocol)	IV	Adult
Atrial flutter	20-50 mg/min until arrhythmia controlled	Preexcited atrial flutter	IV	Adult
Polymorphic ventricular tachycardia	20-50mg/min IV (max 17mg/kg)	Non-torsades PMVT, baseline QT not prolonged	IV	Adult
Polymorphic ventricular tachycardia	15mg/kg IV over 30-60min	Non-torsades PMVT	IV	Pediatric
Wolff–Parkinson–White syndrome	20-50mg/min until arrhythmia suppressed	Wide-complex or AF with pre-excitation	IV	Adult

See Also

• Antiarrhythmics