Abstract
Species differences in oral bioavailability are occasionally observed in drug development phases. They are most likely due to differences in gastrointestinal physiological parameters such as gastrointestinal pH, gastric emptying rate, intestinal transit time, bile acid concentration, and hepatic and intestinal first-pass effect between species. Therefore, to correctly predict human oral bioavailability of a drug, it is still necessary to evaluate the oral absorption profiles of experimental animals and to understand their gastrointestinal physiologies. We investigated the oral absorption profiles of DX-9065, a low-permeability compound, in in vitro and in vivo studies, and we examined several unique formulations to improve its oral absorption. Here, we give examples of species differences in drug absorption by reviewing our preclinical and clinical data for DX-9065.
