Onset of Action for IV Procainamide in Ventricular Tachycardia

Pharmacokinetics and Administration

• The American College of Cardiology recommends procainamide as a Class Ia antiarrhythmic drug with intermediate onset and offset kinetics of membrane sodium channel blockade 1
• IV procainamide is typically administered as a loading infusion of 10-15 mg/kg at a rate of 20 mg/min, with a maintenance infusion of 1-4 mg/min 1, 3
• More recent guidelines suggest administration at rates of 20-50 mg/min until arrhythmia suppression, hypotension occurs, QRS prolongs by 50%, or a maximum dose of 17 mg/kg is reached 4, 5

Clinical Considerations

• The American College of Cardiology indicates procainamide is indicated for life-threatening ventricular arrhythmias but is usually not the drug of first choice 1, 2
• Procainamide may be used when other treatments have failed or are contraindicated, or for wide complex tachycardias of uncertain mechanism 3, 6

Monitoring and Adverse Effects

• Close monitoring is essential during administration due to potential adverse effects, including bradycardia 4
• The American College of Cardiology warns of potential adverse effects, including torsades de pointes, especially in patients with renal insufficiency 1, 3
• Blood pressure should be monitored continuously during administration 4

Important Caveats

• Patients with renal insufficiency may develop high levels of N-acetyl-procainamide (NAPA, an active metabolite) and are at increased risk for torsades de pointes 1
• Procainamide should be avoided in patients with QT prolongation and congestive heart failure 4, 5