Basic Studies on Formulation, Method of Preparation and Characterization of Water-in-Oil-in-Water Type Multiple Emulsions Containing Vancomycin

摘要

A method of preparing a stable water-in-oil-in-water type multiple emulsion (w/o/w emulsion) as a carrier of peptides was sought by studying rotation rate of homogenizer, mixing ratio of each component and concentrations of surfactants. We used "Lipiodol Ultra-Fluid? and isoropyl myristate oil mixture (4.5:5.5)" for an oil phase of the w/o/w emulsion to minimize the difference in specific gravity between this phase and an aqueous phase and to reduce the viscosity of the former, w/o/w emulsions entrapping vancomycin hydrochloride in their internal aqueous phases were prepared by a modified two-stage enmlsificntion procedure and their particle size, entrapment efficiency, viscosity, separation and drug release property studied. The particle size of the w/o/w emulsion was smaller with an increase in rotation rate at an emulsification stage (96.3 + 31.8 ftm at lOOOrpm and 2.81±1.37/im at 20000rpm), but its entrapment efficiency was slightly reduced with rate increase. The best mixing ratio of internal aqueous phase:oil phase:external aqueous phase was 1:4:5. For surfactants, HCO-40 (5% (w/v)) and Phironic F-88 (5% (w/v)) were dissolved in the oily and the external aqueous phase, respectively. Drug release from the w/o/w emulsion was extremely slow and sustained, and that property tended to be faster with a decrease in their particle size (0% at 96.3/im and 2.97 + 0.41% at 2.81 fim). The stability of w/o/w emulsion of 10 fim diameter was good from observations of optical and scanning electron microphotographs and measurement of w/o/w emulsion diameters. The w/o/w emulsion prepared in this study is viewed as a possible carrier of water-soluble drugs.