Pharmaceutical and biotechnological applications of multiple emulsions

Multiple emulsions are polydispersed systems characterized by the co-existence of both oil in water and water in oil emulsions. This complex system is stabilized by the presence of lipophilic and hydrophilic surfactants which ratio is very important to achieve stable multiple emulsion. Between water-in-oil-in-water (w/o/w) and oil-in-water-in-oil (o/w/o) type multiple emulsions the former has great potential application in the pharmaceutical field in order to obtain both novel and simple delivery systems. Herein emphasis is given on the use of multiple emulsions in pharmaceutics. For instance, in the wide range of pharmaceutical and biotechnological applications, the use of multiple emulsions to obtain enzyme immobilization, transdermal delivery, taste masking, prolonged drug delivery increase of bioavailability of the drug and the delivery of proteins and peptides will be reviewed. It is noteworthy that multiple emulsions can also be used as intermediate step in the production of micro- and nano-particulate systems able to control drug release. At this regard a paragraph of this chapter will describe the microencapsulation methods involving multiple emulsions