Relationship between Passive Permeability, Efflux, and Predictability of Clearance from In Vitro Metabolic Intrinsic Clearance

Abstract

ABSTRACT:In vitro intrinsic metabolic clearance (CL int ) is used routinely for compound selection in drug discovery; however, in vitro CL int often underpredicts in vivo clearance (CL). Forty-one proprietary compounds and 16 marketed drugs were selected to determine whether permeability and efflux status could influence the predictability of CL from in vitro CL int obtained from liver microsomal and hepatocyte incubations. For many of the proprietary compounds examined, rat CL was significantly underpredicted using the well stirred model incorporating both fraction of unbound drug in blood and fraction of unbound drug in the microsomal or hepatocyte incubation. Further analysis revealed that the accuracy of the prediction was differentiated by permeability and P-glycoprotein-(Pgp) and mouse breast cancer resistance protein (mBcrp)-mediated efflux. For proprietary compounds with passive permeability greater than 5 ؋ 10 ؊6 cm/s and efflux ratios less than 5 in both P-gp-and mBcrp-expressing cells, CL int provided reasonable prediction. The average -fold error (AFE) was 1.8 for rat liver microsomes (RLMs) and 2.3 for rat hepatocytes. In contrast, CL was dramatically underpredicted for compounds with passive permeability less than 5 ؋ 10 ؊6 cm/s; AFEs of 54.4 and 29.2 were observed for RLM and rat hepatocytes, respectively. In vivo CL was also underpredicted for compounds that were good efflux substrates (permeability >5 ؋ 10 ؊6 cm/s). The AFEs were 7.4 and 8.1for RLM and rat hepatocytes, respectively. A similar relationship between permeability, efflux status, and human CL prediction reported in the literature was observed for 16 marketed drugs. These data show that permeability and efflux status are determinants for the predictability of CL from in vitro metabolic CL int .In vitro metabolic clearance (CL int ) derived from liver microsomal incubations is used routinely to aid compound selection in drug discovery. Hepatocytes, which possess intact cellular membranes, complete enzymatic systems, and cofactors, have also become a common option for determination of CL int . Successful prediction of in vivo clearance (CL) from CL int in liver microsomes or hepatocytes has been reported for some compounds. Obach (1999) reported that CL was predicted within a 2-fold error for 16 of 29 compounds from CL int in human liver microsomes using the well stirred model incorporating both fraction of unbound drug in blood (fu b ) and fraction of unbound drug in the microsomal or hepatocyte incubation (fu inc ).Likewise, CL int from human hepatocytes provided prediction within a 2-fold error for 11 of 37 (Brown et al., 2007) or 23 of 56 compounds (Riley et al., 2005). However, a tendency toward underprediction was observed for many drugs (Obach, 1999;Ito and Houston, 2004;Riley et al., 2005;Brown et al., 2007;Stringer et al., 2008). Marked underprediction of CL from in vitro metabolic CL int in humans and/or animals has been reported for compounds such as montelukast, troglitazone, and quinotolast (Naritomi et al., 2001(Naritomi e...

Comparison of Cryopreserved HepaRG Cells with Cryopreserved Human Hepatocytes for Prediction of Clearance for 26 Drugs

“…At present, the cause of this rate limitation can only be speculated on. Huang et al (2010) demonstrated that underprediction of a set of in-house compounds by hepatocytes was due to biliary efflux in vivo, a phenomenon that is not accounted for in in vitro systems; however, in the present study, this is unlikely to apply because substrates of transporters (particularly P-glycoprotein) were avoided. More appropriate to the drugs used in this study, Foster et al (2011) speculated that clearance dependence in prediction of CL int may be due to a capacity limitation, such as cofactor exhaustion or, alternatively, permeation rate limitation in vitro.…”

Multidrug Resistance-Associated Protein 3 Plays an Important Role in Protection against Acute Toxicity of Diclofenac

“…DCF has high passive permeability, therefore its uptake into tissues should not be limited by active transport processes (Huang et al, 2010). The elevated DCF and lower OH-DCF plasma concentrations in KO compared with WT (Fig.…”

In vitro membrane binding and protein binding (IAM MB/PB technology) to estimate in vivo distribution: applications in early drug discovery

“…Lipophilicity has been recognised for a long time as the principal parameter that influences solubility [20,21], permeability [22], tissue binding, protein binding [23,24], toxicity [10], promiscuity [1], clearance [25] etc. Several ligand efficiency parameters contain the lipophilicity and propose to consider the potency relative to the lipophilicity of the compounds, such as Ligand Lipophilicity Efficiency, LLE [7,26].…”