In this study we tried to prepare stable water-in-oil-in-water (W/O/W) emulsions using polyglycerol polyricinoleate (PGPR) as a hydrophobic emulsifier and whey protein isolate (WPI) as a hydrophilic emulsifier. At first, water-in-oil (W/O) emulsions was prepared, and then 40 wt% of this W/O emulsion was homogenized with 60 wt% aqueous solution of different WPI contents (2, 4, and 6 wt% WPI) using a high-pressure homogenizer (14 and 22 MPa) to produce W/O/W emulsions. The mean size of final W/O/W droplets ranged from 3.3 to 9.9 microm in diameter depending on the concentrations of PGPR and WPI. It was shown that most of the W/O/W droplets were small (<5 microm) in size but a small population of large oil droplets (d > 20 microm) was also occasionally observed. W/O/W emulsions prepared at the homogenization pressure of 22 MPa had a larger mean droplet size than that prepared at 14 MPa, and showed a microstructure consisting of mainly approximately 6 to 7-microm droplets. When a water-soluble dye PTSA as a model ingredient was loaded in the inner water phase, all W/O/W emulsions showed a high encapsulation efficiency of the dye (>90%) in the inner water phase. Even after 2 wk of storage, >90% of the encapsulated dye still remained in the inner water phase; however, severe droplet aggregation was observed at relatively high PGPR and WPI concentrations.

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The effect of cycloamylose on the aqueous solubility of flurbiprofen was investigated. To improve the solubility and bioavailability of flurbiprofen (poor water solubility), a solid dispersion was spray dried with a solution of flurbiprofen and cycloamylose at a weight ratio of 1:1. The physicochemical properties of solid dispersions were investigated using SEM, DSC, and X-ray diffraction. The dissolution and bioavailability in rats were evaluated compared with a commercial product. Cycloamylose increased solubility of flurbiprofen approximately 12-fold and dissolution of it by 2-fold. Flurbiprofen was present in an unchanged crystalline state, and cycloamylose was a solubilizing agent for flurbiprofen in this solid dispersion. Furthermore, the dispersion gave higher AUC and C(max) values compared with the commercial product, indicating that it improved the oral bioavailability of flurbiprofen in rats. Thus, the solid dispersion may be useful to deliver flurbiprofen with enhanced bioavailability without changes in crystalline structure.