STUDY OBJECTIVE: To evaluate P-glycoprotein (P-gp)-mediated renal drug interactions in an in vitro model of tubular secretion. DESIGN: In vitro experiment. SETTING: University-affiliated pharmacokinetics laboratory. CELL LINES: Madin-Darby canine kidney (MDCK), multidrug-resistant-1 (MDR1)-MDCK, and human colon carcinoma (Caco-2) cells. INTERVENTION: Transepithelial transport (basolateral-to-apical and apical-to-basolateral) of cimetidine was assessed in the absence and presence of various concentrations of the P-gp inhibitors itraconazole and PSC-833 in a renal P-gp cell culture model (MDR1-MDCK). MEASUREMENTS AND MAIN RESULTS: Apparent permeability of cimetidine was characterized, and level of P-gp expression was determined by Western blot analysis, in MDCK (wild type), MDR1-MDCK, and Caco-2 cells (for relative comparison). In the presence of PSC-833, cimetidine's apparent permeability value for basolateral-to-apical transport decreased from 2.96 to 1.15 x 10(-6) cm/second, coupled with a decrease in efflux ratio from 2.36 to 1.80. The effect of itraconazole was concentration dependent, with cimetidine's apparent permeability value for basolateral-to-apical transport decreasing from 3.96 to 1.92 x 10(-6) cm/second (p < 0.05), resulting in a 50% decrease in efflux ratio. Expression of P-gp was negligible in MDCK (wild-type) cells, but high-level expression was confirmed in both MDR1-MDCK and Caco-2 cells. CONCLUSION: P-glycoprotein plays a significant role in the renal tubular secretion of organic cations such as cimetidine, and the high level of P-gp expression in MDR1-MDCK cells makes this a well-suited model for evaluating mechanisms of renal drug interactions.
STUDY OBJECTIVE: To evaluate P-glycoprotein (P-gp)-mediated renal drug interactions in an in vitro model of tubular secretion. DESIGN: In vitro experiment. SETTING: University-affiliated pharmacokinetics laboratory. CELL LINES: Madin-Darby canine kidney (MDCK), multidrug-resistant-1 (MDR1)-MDCK, and humancolon carcinoma (Caco-2) cells. INTERVENTION: Transepithelial transport (basolateral-to-apical and apical-to-basolateral) of cimetidine was assessed in the absence and presence of various concentrations of the P-gp inhibitors itraconazole and PSC-833 in a renal P-gp cell culture model (MDR1-MDCK). MEASUREMENTS AND MAIN RESULTS: Apparent permeability of cimetidine was characterized, and level of P-gp expression was determined by Western blot analysis, in MDCK (wild type), MDR1-MDCK, and Caco-2 cells (for relative comparison). In the presence of PSC-833, cimetidine's apparent permeability value for basolateral-to-apical transport decreased from 2.96 to 1.15 x 10(-6) cm/second, coupled with a decrease in efflux ratio from 2.36 to 1.80. The effect of itraconazole was concentration dependent, with cimetidine's apparent permeability value for basolateral-to-apical transport decreasing from 3.96 to 1.92 x 10(-6) cm/second (p < 0.05), resulting in a 50% decrease in efflux ratio. Expression of P-gp was negligible in MDCK (wild-type) cells, but high-level expression was confirmed in both MDR1-MDCK and Caco-2 cells. CONCLUSION:P-glycoprotein plays a significant role in the renal tubular secretion of organic cations such as cimetidine, and the high level of P-gp expression in MDR1-MDCK cells makes this a well-suited model for evaluating mechanisms of renal drug interactions.
Authors: Kathleen Köck; Markus Grube; Gabriele Jedlitschky; Lena Oevermann; Werner Siegmund; Christoph A Ritter; Heyo K Kroemer Journal: Clin Pharmacokinet Date: 2007 Impact factor: 6.447