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Use of uptake intrinsic clearance from attached rat hepatocytes to predict hepatic clearance for poorly permeable compounds

We previously reported that the accuracy of clearance (CL) prediction could be differentiated by permeability. CL was drastically under-predicted by in vitro metabolic intrinsic clearance (CLint) for compounds with low permeability (<5 × 10−6 cm/s). We determined apparent uptake CLint by measuring initial disappearance from medium using attached rat hepatocytes and metabolic CLint by measuring parent depletion in suspended rat hepatocytes (cells and medium). Uptake and metabolic CLint were comparable for highly permeable metabolic marker compounds. In contrast, uptake CLint was 3- to 40-fold higher than metabolic CLint for rosuvastatin, bosentan, and 15 proprietary compounds, which had low permeability, suggesting that uptake could be a rate-determining step in hepatic elimination for these poorly permeable compounds. The prediction of hepatic CL was improved significantly when using uptake CLint for the compounds with low permeability. The average fold error was 2.2 and 6, as opposed to >11 and >47 by metabolic CLint, with and without applying a scaling factor of 4, respectively. Uptake CLint from attached hepatocytes can be used as an alternative approach to predict hepatic clearance and to understand the significance of hepatic uptake in elimination in an early drug discovery setting.