 Acecainide is considered comparable in activity to its parent compound; however, acecainide levels will vary widely.Serum levels of acecainide increase in patients on chronic procainamide therapy, particularly in those with renal impairment.The average serum concentration ratio of acecainide to procainamide is 0.8 to 1.2, depending on a genetically determined tendency to acetylate procainamide rapidly or slowly.