Neel Deferm (1), Sagnik Chatterjee (2), Lysiane Richert (3), Peter de Witte (4), Thomas Bouillon (1), Pieter Annaert (1)
(1) Drug Delivery and Disposition, KU Leuven Department of Pharmaceutical and Pharmacological Sciences, Leuven, Belgium (2) Biocon Bristol-Myers Squibb R&D Center (BBRC), Syngene International Ltd., Bangalore, India (3) KaLy-Cell, Plobsheim, France (4) Laboratory for Molecular Biodiscovery, KU Leuven Department of Pharmaceutical and Pharmacological Sciences, Leuven, Belgium
Objectives: To develop a physiological model which describes hepatic uptake, metabolism and biliary excretion of the bile acids (BAs) chenodeoxycholic acid (CDCA) and its glycine-conjugate glycochenodeoxycholic acid (GCDCA) in sandwich-cultured human hepatocytes (SCHH) and to utilize it to quantify differences in estimated kinetic parameters between day-2 and day-6 cultures.
Methods: In vitro disposition data were obtained by incubating SCHH with 2.5, 10 or 25 µM CDCA. Incubation buffers containing CDCA and GCDCA were collected, followed by cell lysis to determine intracellular levels. Additionally, biliary excretion of CDCA and GCDCA were determined. An ordinary differential equation (ODE) model was fitted to concentration and amount-time profiles with NONMEM (ICON plc) Version VII level 3.0 using a proportional error model and the first-order conditional estimation with interaction (FOCE+I) method for analysis [1]. The model includes compartments representing the buffers, cells, bile and cells+bile with compound distributed among them through linear processes. Model selection was based on the log-likelihood criterion, goodness-of-fit plots, and scientific plausibility. Initial parameter estimations were obtained from simulations using Berkeley-Madonna v8.3.23.0. Culture time (day-2 or day-6) and phase (loading or efflux) were implemented as dichotomous covariates in the dataset. Statistical significance of covariate effects on kinetic parameters was assessed using a stepwise covariate method involving testing of covariate relationships in a forward inclusion (reduction of objective function value (∆OFV) of 6.63; P<0.01) and backward exclusion (∆OFV of 10.8; P<0.001).
Results: A mechanistic ten-compartment disposition model was developed which adequately described the in vitro disposition of CDCA and GCDCA. Total (passive + active) intrinsic unbound uptake and efflux clearance of CDCA were estimated to be 4 (± 6%) µL/min/106 cells (CLint,u,up,CDCA) and 2 (± 1%) µL/min/106 cells (CLint,u,eff,CDCA), while estimates of the total (passive + active) intrinsic unbound uptake and efflux clearance of GCDCA were 0.5 (± 1%) µL/min/106 cells (CLint,u,up,GCDCA) and 0.6 (± 2%) µL/min/106 cells (CLint,u,eff,GCDCA). Total (passive + active) intrinsic unbound biliary clearances of CDCA and GCDCA were estimated at 6 (± 4%) µL/min/106 cells (CLint,u,bile,CDCA) and 5 (± 12%) µL/min/106 cells (CLint,u,bile,GCDCA), whereas the estimate of intrinsic unbound metabolic clearance (CLint,u,met) of CDCA was 18 (± 7%) µL/min/106 cells. Covariate analysis showed a statistically significant effect (p < 0.01) of culture time on CLint,u,eff,GCDCA (day-2: 0.6 (± 1%) µL/min/106 cells, day-6: 1.7 (± 2%) µL/min/106 cells) and CLint,u,met (day-2: 17.7 (± 3%) µL/min/106 cells, day-6: 7.2 (± 11%) µL/min/106 cells).
Conclusions: Modeling of in vitro BA disposition suggests that the hepatic elimination of CDCA is mostly dominated by its conversion to GCDCA, while biliary excretion clearance of unchanged CDCA represents about 28% of the metabolic clearance.
References:
[1] Beal SL, Sheiner LB, Boeckmann AJ & Bauer RJ (Eds.) NONMEM Users Guides. 1989-2011. Icon Development Solutions, Ellicott City, Maryland, USA
Reference: PAGE 27 (2018) Abstr 8541 [www.page-meeting.org/?abstract=8541]
Poster: Drug/Disease Modelling - Absorption & PBPK