Mechanism of the intestinal absorption of drugs from oil in water emulsions. V. Enhanced absorption of methyl orange adsorbed at oil/water interface in emulsions.

Abstract

Absorption of drug which is adsorbed at oil-water interface in emulsion was studied in rat large intestine using in situ recirculation technique. Methyl orange (MO) which was chosen as a model drug, was adsorbed at oil-water interface by the coexistence with emulsifiers. Its physico-chemical states were varied with oil concentrations. MO was absorbed well more than ten times from emulsion system compared with that from aqueous solution. Enhancement of MO absorption was interrelated with the adsorption of MO at oil-water interface. Furthermore it was found that not only quantity but also quality of MO adsorption at oil-water interface affected on the absorption rate of MO. Critical oil concentration which showed maximum absorption rate, depended on the length of the absorption site and the degree of adsorption of oil droplets on mucosal membrane was also rate-determining factor for MO absorption from emulsion system.