Development of in vitro pharmacokinetic screens using Caco-2, human hepatocyte, and Caco-2/human hepatocyte hybrid systems for the prediction of oral bioavailability in humans

J Biomol Screen. 2007 Dec;12(8):1084-91. doi: 10.1177/1087057107308892. Epub 2007 Nov 7.

Abstract

In this study, in vitro systems were used to build 2 pharmacokinetic models that predict human oral bioavailability: the Caco-2/hepatocyte combination model and the Caco-2/hepatocyte hybrid model. Data obtained in vitro on Caco-2 cell permeability and hepatocyte clearance are routinely used to predict the fraction of absorption after oral administration and the extent of first-pass metabolism, respectively. In the Caco-2/hepatocyte combination model, results from a Caco-2 cell permeability assay and a hepatocyte clearance assay were combined to project oral bioavailability. Comparison of oral bioavailabilities predicted by the combination model and reported oral bioavailabilities in humans for 30 marketed compounds resulted in a modest correlation (r(2) = 0.66). The Caco-2/hepatocyte hybrid model, as previously reported, joins the Caco-2 and hepatocyte clearance systems into 1 assay. Improvements to the previous model were made by incorporating an elimination phase into the Caco-2/hepatocyte hybrid model. In the new hybrid model, the compound was added to a Caco-2-containing donor compartment and allowed to permeate for 2 h to a hepatocyte-containing receiver compartment. Subsequently, to mimic an elimination phase, the donor compartment was removed, and permeated compound was incubated with hepatocytes alone for an additional 3 h. The area under the concentration versus time curve (AUC) was determined for each of the same 30 marketed compounds assessed by the combination model. A linear regression analysis comparing the in vitro AUCs and reported oral bioavailabilities in humans showed a reasonable correlation (r(2) = 0.73). This study demonstrates that the Caco-2/hepatocyte hybrid model is more favorable and further proves the potential and feasibility of using in vitro screenings for the prediction of in vivo pharmacokinetics in humans.

MeSH terms

  • Administration, Oral
  • Area Under Curve
  • Biological Availability
  • Caco-2 Cells
  • Cell Membrane Permeability / drug effects
  • Dose-Response Relationship, Drug
  • Drug Evaluation, Preclinical / methods*
  • Hepatocytes / drug effects*
  • Hepatocytes / metabolism*
  • Humans
  • Models, Biological*
  • Pharmacokinetics*
  • Reference Standards
  • Time Factors