TY - JOUR T1 - Disposition of gemfibrozil and gemfibrozil acyl glucuronide in the rat isolated perfused liver. JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 984 LP - 989 VL - 24 IS - 9 AU - B C Sallustio AU - B A Fairchild AU - K Shanahan AU - A M Evans AU - R L Nation Y1 - 1996/09/01 UR - http://dmd.aspetjournals.org/content/24/9/984.abstract N2 - Acyl glucuronides are reactive electrophilic metabolites and in vivo are readily hydrolyzed, undergo intramolecular rearrangement, and bind covalently to proteins. The isolated perfused liver preparation, using male Sprague-Dawley rats, was used to examine the hepatic disposition of the fibrate hypolipidemic agent gemfibrozil and its acyl glucuronide metabolite, 1-O-gemfibrozil-beta-D-glucuronide. Using a recirculating design, erythrocyte-free perfusion medium containing 1% (w/v) albumin was delivered to the liver via the portal vein at a flow rate of 30 ml/min, and for each experiment was spiked with either gemfibrozil (N = 4) or 1-O-gemfibrozil-beta-D-glucuronide (N = 4) at initial concentrations of 120 microM and 21 microM, respectively. In the gemfibrozil perfusions, the mean (SD) total perfusate clearance, half-life, hepatic extraction ratio of gemfibrozil, and the fraction of eliminated gemfibrozil excreted in bile as the glucuronide conjugate were 2.73 (0.30) ml/min, 76.9 (5.6) min, 0.091 (0.012), and 0.347 (0.154), respectively. In the 1-O-gemfibrozil-beta-D-glucuronide perfusions, the mean (SD) total perfusate clearance, half-life, hepatic extraction ratio, and fraction excreted in bile as the glucuronide conjugate were 19.5 (2.1) ml/min, 8.7 (0.9) min, 0.649 (0.068), and 0.534 (0.077), respectively. The higher hepatic extraction ratio for 1-O-gemfibrozil-beta-D-glucuronide could mostly be attributed to its higher unbound fraction in perfusate (0.182), compared with that of the parent drug (0.004), because the conjugate had a lower intrinsic clearance (305 ml/min) compared with the aglycone (751 ml/min). Control perfusions, conducted in the absence of a liver, showed negligible degradation of 1-O-gemfibrozil-beta-D-glucuronide over 90 min. However, in the presence of a liver, approximately 25% of 1-O-gemfibrozil-beta-D-glucuronide added to perfusate was hydrolyzed to gemfibrozil over 90 min. The study demonstrates the importance of the liver in the formation, uptake, hydrolysis, and excretion of 1-O-gemfibrozil-beta-D-glucuronide. ER -