Interspecies differences in gastrointestinal physiology affecting the in vivo performance of oral pharmaceutical solid dosage forms

Various physiological factors in the gastrointestinal (GI) tract affect the in vivo performance of orally administered dosage forms. In this review article, we summarize the formulation-related interspecies differences (particularly under the fasted state) between humans and laboratory animals. In particular, we discuss the differences in fluid characteristics in the stomach and small intestine, transit of dosage forms in the gut, and drug permeation through the intestinal epithelium after release from dosage forms. Further, we provide several case examples of oral drug formulations that were affected by species-specific differences in GI physiology between laboratory animals and humans that have been discussed at the consortium of Academy of Pharmaceutical Science and Technology, Japan. In these examples, species-specific differences in gut physiological parameters between humans and animals greatly affected the in vivo performance of dosage forms.