Routes, mechanisms, and magnitude of procainamide hydrochloride excretion were examined. In normal man and dogs, renal excretion averaged 65% in 6 hours and 90% in 12 hours and mean plasma half-time was 2.85 ± 0.25 hours. Patients with renal disease had prolonged plasma half-time (5.85 ± 0.62 hours; P <.001) and decreased sixhour urine excretion (40.8 ± 1.8%; P <.001). Excretion was directly related to creatinine clearance. In experimental animals, increasing urine pH resulted in decreased renal procainamide clearance, but increasing urine flow rate with diuretics produced no change in clearance. Active biliary excretion occurred (bile plasma ratios—2.0) but total bile excretion and bile clearance were insignificant. Procainamide excretion is primarily renal and patients with renal impairment or alkalinized urine require reduced dosage.
Weily HS, Genton E. Pharmacokinetics of Procainamide. Arch Intern Med. 1972;130(3):366-369. doi:10.1001/archinte.1972.03650030046011