TY - JOUR T1 - Altered Hepatobiliary Disposition of Tolvaptan and Selected Tolvaptan Metabolites in a Rodent Model of Polycystic Kidney Disease JF - Drug Metabolism and Disposition JO - Drug Metab Dispos DO - 10.1124/dmd.118.083907 SP - dmd.118.083907 AU - James John Beaudoin AU - Jacqueline Bezencon AU - Yanguang Cao AU - Katsuhiko Mizuno AU - Sharin E Roth AU - William J Brock AU - Kim L.R. Brouwer Y1 - 2018/01/01 UR - http://dmd.aspetjournals.org/content/early/2018/11/30/dmd.118.083907.abstract N2 - Tolvaptan, a vasopressin V2-receptor antagonist, has demonstrated efficacy in slowing kidney function decline in patients with autosomal dominant polycystic kidney disease (ADPKD). In the pivotal clinical trial, the incidence of elevated liver enzymes was higher in patients receiving tolvaptan compared to placebo. Adjudication by a panel of expert hepatologists concluded a causal link of tolvaptan to liver injury in patients with ADPKD. An ex situ isolated perfused liver (IPL) study of tolvaptan disposition was undertaken in a rodent model of ADPKD, the polycystic kidney (PCK) rat (n=5), and compared to wild-type Sprague-Dawley (WT) rats (n=6). Livers were perfused with tolvaptan, followed by a tolvaptan-free washout phase. Total recovery (mean±S.D.% dose; PCK vs. WT) of tolvaptan and two metabolites, DM-4103 and DM-4107, quantified by LC-MS/MS, was 58.14±24.72% vs. 43.40±18.11% in liver, 20.10±9.15% vs. 21.17±12.51% in outflow perfusate, and 0.08±0.01% vs. 0.39±0.32% in bile. DM-4103 recovery (mean±S.D.% dose) was decreased in PCK vs. WT bile (<0.01±<0.01 vs. 0.02±0.01%; p=0.0037), and DM-4107 recovery was increased in PCK vs. WT outflow perfusate (1.60±0.57% vs. 0.43±0.29%; p=0.0017). A pharmacokinetic compartmental model assuming first-order processes was developed to describe the rate vs. time profiles of tolvaptan and DM-4103+DM-4107 in rat IPLs. The model-derived estimate of tolvaptan's biliary clearance was significantly decreased in PCK compared to WT IPLs. The model predicted greater hepatocellular concentrations of tolvaptan and DM-4103+DM-4107 in PCK compared to WT IPLs. Increased hepatocellular exposure to tolvaptan and metabolites may contribute to the hepatotoxicity in patients with ADPKD treated with tolvaptan. ER -