[Fat-soluble vitamins: Intestinal absorption].

General principals of drug absorption and bioavailability after the oral administration are discussed in each process of drug release and dissolution from the preparation, such as gastric emptying time and flow of drug in intestinal track, transport through intestinal mucosal microvilli, and the first pass effect of drug elimination in the liver. Character of lipid soluble vitamins in these absorption processes are elucidated with the low solubility in water and solubilization in bile acids micelle. Our studies on dl-alpha-tocopherol solubilization into micelles of bile acids and a detergent and the rat intestinal absorption by perfusion of the micellar solutions are introduced. Faster absorption of the tocopherol solubilized in bile acid micelles, than polysorbate 80, was observed in spite of the less solubilizing abilities of bile acids. Relatively high dependency on volume flow through the intestinal wall was observed in the absorption rate of tocopherol. The dependency is larger in bile acid micelles having smaller size than polysorbate 80 having large size.