Development of a high-throughput in vitro assay using a novel Caco-2/rat hepatocyte system for the prediction of oral plasma area under the concentration versus time curve (AUC) in rats

IntroductionPreviously, we have shown that a novel Caco-2/human hepatocyte system is a useful model for the prediction of oral bioavailability in humans. In this study, we attempted to use a similar system in a high-throughput screening mode for the selection of new compound entities (NCE) in drug discovery.MethodsA total of 72 compounds randomly selected from three different chemotypes were dosed orally in rats. In vivo plasma area under the concentration versus time curve (AUC) from 0–6 h of the parent compound was determined. The same compounds were also tested in the Caco-2/rat hepatocyte system. In vitro AUC from 0–3 h in the Caco-2 rat hepatocyte system was determined.ResultsThe predictive usefulness of the Caco-2/rat hepatocyte system was evaluated by comparing the in vivo plasma AUC and the in vitro AUC. Linear regression analysis showed a reasonable correlation (R2 = 0.5) between the in vivo AUC and the in vitro AUC. Using 0.4 μM h in vivo AUC as a cut-off, compounds were categorized as either low or high AUC. The in vitro AUC successfully matched the corresponding in vivo category for sixty-three out of seventy-two compounds.DiscussionThe results presented in this study suggest that the Caco-2/rat hepatocyte system may be used as a high-throughput screen in drug discovery for pharmacokinetic behaviors of compounds in rats.