The presented study aimed to develop self-dispersing drug delivery systems based on natural phospholipids. A comprehensive investigation on miscibility was therefore carried out on mixtures containing one or two phosphatidylcholines as emulsifying excipients, ethanol 96% as co-solvent and different oils and fats. The soybean diacyl phosphatidylcholines Phospholipon90G and LipoidS75 as well as the monoacyl phosphatidylcholine LipoidSLPC80 were investigated for their maximum incorporation in the different lipids. Homogeneity and stability of the mixtures were determined according to their macroscopic appearance and by polarized light microscopy. Homogeneous formulations could be prepared with all three phosphatidylcholines in combination with medium chain triglycerides and semisolid hard fat. Phospholipon90G and LipoidS75 further yielded homogeneous formulations with rapeseed oil, soybean oil and diacetylated monoglycerides. Small- and wide-angle x-ray scattering studies indicated the presence of reverse micelles or (liquid) crystalline structures in the mixtures. Formulations with oils and Phospholipon90G or LipoidSLPC80 easily dispersed in Simulated Gastric Fluid making these mixtures suitable as self-dispersing formulations.
Keywords: Liquid crystalline phases; Miscibility; Phosphatidylcholine; Phospholipids; Polarized light microscopy; Reverse micelles; Self-emulsifying drug delivery systems; Small-angle x-ray scattering.
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