Overview

• Compound related to local anesthetic procaine used in treatment of reentrant tachyarrhythmias

Dosing

• Procainamide infusion 2-6 mg/min, consider loading 6-13 mg/kg until arrhythmia is controlled, QRS prolongs >50% or hypotension occurs

Distribution and metabolism

• Steady state is reached within a few hours of IV infusion and 24 hours with PO.
• Metabolism is to N-acetyl procainamide (NAPA) which is genetically determined (16-20% in “slow” acetylators and 25-30% in “fast” acetylators).
• NAPA has significant antiarrhythmic action (i.e. class III via potassium channel blockade). High levels of NAPA in “fast” acetylators can prolong QT and induce Torsades. NAPA is renally excreted.

Therapeutic drug monitoring

• Measure both procainamide and NAPA levels, particularly in patients at risk for increased NAPA levels (renal failure, heart failure).

Therapeutic plasma concentrations

• 4-10 mcg/mL

Dose adjustments

• Dose should be reduced in hepatic disease, renal disease and heart failure.

References

• Zipes, et al. Braunwald’s Heart Disease, A Textbook of Cardiovascular Medicine, 11 th edition, Chapter 36, Therapy of Cardiac Arrhythmias.
• Campbell TJ, Williams KM. Therapeutic drug monitoring: antiarrhythmic drugs. J Clinical Pharmacol. 2001;52:21S-35S.