Simultaneous quantification of procainamide and N-acetylprocainamide with high-performance liquid chromatography.

A rapid, precise and specific method for the simultaneous determination of procainamide and N-acetylprocainamide (NAPA) in plasma using high-performance liquid chromatography is described. N-Formylprocainamide was utilized as internal standard. The coefficients of variation of the method for both procainamide and NAPA were 3.6% in the range of plasma levels to be expected clinically. The method is especially useful for rapid determination of acetylator phenotype in patients requiring procainamide for control of arrhythmias.