Electromotive versus passive diffusion of mitomycin C into human bladder wall: concentration-depth profiles studies

The objectives of these investigations were: (a) to make a preliminary study to assess concentration-depth profiles of mitomycin C (MMC) in the bladder wall at specified time intervals after passive diffusion (PD); and (b) to conduct a major study to compare concentration-depth profiles after PD and electromotive drug administration (EMDA) of MMC. Full thickness sections of viable human bladder wall were placed in two-chamber cells with urothelium exposed to donor compartments containing 40 mg of MMC in 100 ml of 0.96% NaCl solutions and with serosa-facing receptor compartments containing 0.9% NaCl solutions. In the preliminary study during each of nine experimental sessions, five sections of bladder wall were individually exposed to MMC for either 5, 15, 30, 45, or 60 min. In the major study, an anode and a cathode were sited in the donor and receptor compartments, and 14 paired experiments--current (20 mA)/no current--were conducted over a 30-min period. Bladder wall sections were cut serially into 40-microm slices parallel to the urothelium and analyzed by high-performance liquid chromatography for MMC concentration (microg/g wet tissue weight). Tissue viability and morphology and MMC stability were assessed by trypan-blue exclusion test, histological examination, and mass spectrometry analysis. In the preliminary study (PD only), mean MMC concentrations (microg) at 5, 15, 30, 45, and 60 min were: (a) for urothelium, 15.3, 60.0, 58.2, 60.1, and 57.8, respectively; (b) for lamina propria, 2.2, 18.9, 19.3, 16.1, and 17.3, respectively; and (c) for muscularis, 0.4, 2.0, 1.8, 1.3, and 2.4, respectively. In the comparative study, MMC concentrations and coefficients of variation (CV) were as follows: (a) for urothelium after PD, 46.6 with CV = 69%, and after EMDA, 170.0 with CV = 43% (P < 0.0001); (b) for lamina propria after PD, 16.1, with CV = 60%, and after EMDA, 65.6 with CV = 29% (P < 0.0001); and (c) for muscularis after PD, 1.9 with CV = 82%, and after EMDA, 15.9 with CV = 82% (P < 0.0005). All of the bladder sections remained viable, and the chemical structure of MMC was unchanged. It was concluded that EMDA significantly enhances MMC transport into all of the layers of the bladder wall, and sections of viable human bladder are a reliable tool for assessing different modes of drug delivery.