An overview of Preparation, Evaluation and Applications of Multiple Emulsions

Multiple emulsions are also known as emulsions of emulsions, liquid membrane system or double emulsion. Multiple emulsions are polydispersed systems where both oil in water & water in oil emulsions exist simultaneously. This review focuses on preparation, characterization and potential applications of multiple emulsions. Multiple emulsions can be classified as water-in oil-in water (W/O/W) or oil-in-water-in-oil (O/W/O) emulsions. This review described five methods to prepare multiple emulsions viz. two-step emulsification method, modified two-step emulsification method, phase inversion method, membrane emulsification & micro channel emulsification method. The Multiple emulsion is characterized by average globule size & size distribution, area of interfaces, number of globules, rheological evaluation, zeta potential, percentage drug entrapment, In-vitro drug release. Multiple emulsions have been proposed to have numerous uses including their use as prolonged drug delivery system.