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The mean diameter of emulsion droplets prepared using three different emulsifiers (egg yolk lecithin alone, egg yolk lysolecithin alone, and a mixture of egg yolk lecithin and lysolecithin) was investigated. Considering the nasal administration of enteral nutrients or that through gastric/jejunal fistulae, the stability of each emulsion with artificial gastric fluid (pH 1.2) or intestinal fluid (pH 6.8) was investigated. When adding artificial intestinal fluid, all emulsions prepared with various emulsifiers (egg yolk lecithin, egg yolk lysolecithin, soybean lecithin, soybean lysolecithin, DK ester® F-140, and Sunsoft® A-141E) were stable. On the other hand, when adding artificial gastric fluid, emulsions prepared with egg yolk lysolecithin or Sunsoft® A-141E were stable, but there was a reduction in the stability of emulsions prepared with the other emulsifiers, with an increase in the particle size. Based on these results, we prepared an emulsion using a natural component-derived emulsifier for ...

We have developed a new method to determine the marker calcein encapsulated in liposomes using ethanol or propanol instead of Triton X-100. Calcein in ethanol solution was estimated by fluorophotometry with excitation and emission wavelengths of 490 nm and 520 nm, respectively. The fluorescence intensity of calcein solubilized by ethanol was linear in the range of 10 −6−10 −4 mol/L with a correlation coefficient of 0.999. The proposed method, which was accurate and reproducible, was successfully applied to determine the amounts of ethanol-soluble drugs in liposomes.

The preparation and physicochemical properties of lipid vesicles, containing magnetite (Fe3O4) and an anticancer agent (5-fluorouracil) were described. The possibility of using the resulting lipid vesicles as a targeting carrier was examined both in vitro and in vivo. From measurements of viscosity, the observational data in this study were found to be in fairly good accord with the theoretically derived viscosity equation described by Brinkman or Oliver and Ward. The resulting lipid vesicles containing very fine Fe3O4 particles were found to act as rigid spheres in solution. At a field strength of 4000 G, more than 80% of the lipid vesicles infused were found to be retained in the target site of the ear vasculature in rabbits.

The conditions for the preparation of lipid vesicles ((liposomes) by the in-water drying method, one of the microencapsulation techniques, were described in detail. This process consists of the following steps: (I) dispersion of an aqueous solution of the drug to be encapsulated into an organic solvent to yield a water-in-oil emulsion, (II) dispersion of this w/o-type emulsion into an aqueous phase (distilled water), (III) formation of a lipid membrane on the surface of droplets by evaporation of the organic solvent from the oil phase, and (IV) removal of the free marker (drug) by ultracentrifugation or gel filtration through a Sephadex column. In this process, the mean diameter of the vesicles was dependent on the mechanical revolution number necessary for dispersing the w/o-type emulsion into the distilled water. Moreover, the percentage encapsulation of the lipid vesicles increased with the decrease in mechanical revolution number necessary for dispersing the w/o-type emulsion into the distill...