Enhancement of oral bioavailability of d-.ALPHA.-tocopherol acetate by lecithin-dispersed aqueous preparation containing medium-chain triglycerides in rats.

Abstract

In order to evaluate oral dosage forms of d-.alpha.-tocopherol acetate (VEA), d-.alpha.-tocopherol (VE) concentration in the plasma was examined followiing oral administration of three VEA preparations; lecithin-dispersed aqueous preparation, polysorbate 80 (PS-80)-solubilized aqueous solution and soybean oil solution. The lecithin-dispersed preparation gave the highest Cmax and the largest AUC0-24h, while Tmax was delayed. In the thoracic duct fistula rat, no increase in VE plasma concentration was observed after intraduodenal administration of lecithin-dispersed VEA preparation, while VE appeared in the thoracic lymph, indicating that VE is absorbed from the lecithin-dispersed preparation via the lymphatic route. The delayed Tmax and prolonged VE plasma concentration obtained with the lecithin-dispersed preparation in comparison with PS-80-solubilized aqueous solution could be explained by the different route of absorption.