PREPARATION OF MICROEMULSIONS USING POLYGLYCEROL FATTY-ACID ESTERS ASSURFACTANT FOR THE DELIVERY OF PROTEIN DRUGS

Phase diagrams containing the microemulsion region were constructed fo r pseudo-ternary systems composed of polyglycerol fatty acid ester/cos urfactant/Captex 300/water. It was found necessary to add ethanol, 1-p ropanol, or 1-butanol as cosurfactant to produce microemulsions. The r esults also demonstrated microemulsions were only able to form when em ploying polyglycerol fatty acid esters with hydrophile-lipophile balan ces (HLBs) between 8 and 13, such as MO500, MO750, SO750, and ML310. M ost microemulsions were determined to be Winsor type IV by dilution an d dye solubility tests. Microemulsions stored at ambient temperature m aintained constant viscosity, indicating that the system was thermodyn amically stable for long periods. Further, several microemulsion formu lations were demonstrated to be promising for oral delivery of insulin based on the results of stability tests and acid-protection efficienc y.