Comparison of transport of procainamide and N-acetylprocainamide from blood into the intestinal lumen with that into the peritoneal cavity in rats.

Transfer of procainamide and its active metabolite, N-acetylprocainamide (NAPA) from the blood into the intestinal lumen was compared with that into the peritoneal cavity after i.v. administration of procainamide at the dose of 10 mg/kg to rats. The amounts of both drugs transferred from the blood into the intestinal lumen were much greater than those into the peritoneal cavity. The average amounts of procainamide transferred in 2 h into the intestinal lumen and the peritoneal cavity were 12.7% and 1.7% of dose (10 mg/kg), respectively, while those of NAPA were 3.5% and 1.4% of dose. The intestinal and peritoneal clearance values of procainamide were 143.5 and 59.4 ml/h, respectively, and those of NAPA were 32.6 and 13.5 ml/h. The difference in transfer rates across the intestinal and peritoneal membranes may be due to difference in the area of permeative surface and the extent of ionization in the dialysate. Consequently, it is expected that the gastrointestinal dialysis by oral administration of activated charcoal may serve as one of the more useful hemopurification methods than the peritoneal dialysis in procainamide and NAPA intoxication.