Mechanism of the intestinal absorption of drugs from oil-in-water emulsions. VII. Role of bile in the lymphatic transport of lipid-soluble compounds from triolein emulsions.

Abstract

Lymphatic transport of lipid-soluble dye, Sudan Blue, and vitamin A acetate from oil-in-water emulsions was investigated using in situ loop method by the rat small intestine. A natural oil, triolein, which was known to be transported mainly through lymphatic pathway, was chosen as an oil phase of the emulsion. Lymphatic transport of Sudan Blue and vitamin A acetate was very small in the absence of bile. When sodium taurocholate and egg phosphatidylcholine were co-administered with emulsions, lymphatic transport of lipid-soluble compounds were recovered even in bile fistula rats. Addition of one of them could not recover completely the lymphatic transport of lipid-soluble compounds. It was concluded that both bile salts and phosphatidylcholine were necessary for the lymphatic transport of the fat and lipid-soluble compound which interact with oil administered intraluminally. However, overall contribution of lymphatic pathway to their disappearance from the small intestinal lumen is very small, and the main route of their absorption is thought to be the portal pathway.