Comparison of In Vitro-In Vivo Extrapolation of Biliary Clearance Using an Empirical Scaling Factor Versus Transport-Based Scaling Factors in Sandwich-Cultured Rat Hepatocytes

Biliary clearance (CLb) is often underestimated by in vitro-in vivo extrapolation from sandwich-cultured hepatocytes (SCHs). The objective of this study was to compare the performance of a universal correction factor with transporter-based correction factors in correcting underestimation of CLb. The apparent in vitro CLb of a training set of 21 compounds was determined using the SCH model and extrapolated to apparent in vivo CLb (CLb, app). A universal correction factor (10.2) was obtained by a linear regression of the predicted CLb, app and observed in vivo CLb of training set compounds and applied to an independent test set (n = 20); the corrected CLb predictions of 13 compounds were within twofold error of observed values. Furthermore, two transporter-based correction factors (Organic anion transporting polypeptides/multidrug-resistance-related protein 2 and diffusion/P-glycoprotein) were estimated by linear regression analysis of training set compounds. The applications of the two correction factors to the test set resulted in improved prediction precision. In conclusion, both the universal correction factor and transporter-based correction factors provided reasonable corrections of CLb values, which are often underestimated by the SCH model. The use of transporter-based correction factors resulted in an even greater improvement of predictions for compounds with intermediate-to-high CLb values. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:2837-2850, 2013