Lipid based non-aqueous nano emulsions: A review

Oral administration of therapeutic agents represents easiest and most convenient route of drug delivery especially in the case of chronic therapies. Liquid administration of drugs is one of the convenient and often advantageous deliveries, especially when dealing with children or elderly patient whom pill swallowing could be difficult or hazardous. Unfortunately, there are drugs that are not soluble in water, whereas some of water soluble drugs may have unpleasant taste. Moreover there are drugs that are unstable in water or are insoluble in water therefore limiting their incorporation into aqueous formulations. Water free liquid preparation of a number of drugs in question is a key to solve formulation problem. The replacement of the aqueous phase by various other solvents (e.g. dimethyl sufoxide, formamide) offers the great potential of developing emulsion systems exhibiting other physico-chemical properties than conventional emulsion systems. There are two basics strategies that could be considered while searching for stable non-aqueous emulsions. First is to design surfactants having two incompatible blocks, each of which is selectively soluble in either of the immiscible liquids. Second approach is to search a suitable oil immiscible polar liquid that can substantially replace water using emulsifiers. A liquid capable of replacing water in an emulsion should have an appreciable polarity to make it immiscible with oils and make it good solvent for the solvophilic part of surfactant molecules. Theoretically, stabilization mechanisms involved formation of a viscous network in the continuous phase or interface. The present review focuses on non-aqueous nano emulsions system (NANEs).