Self-Emulsifying Formulations: A Pharmaceutical Review

Abstract

The oral route of drug delivery is commonly utilized for administration of medicines and is particularly preferred for the treatment of many chronic diseases which require continuous ingestion over a reasonably prolonged period of time. However the oral delivery of lipophilic drugs presents a major obstacle because of their low aqueous solubility. The aqueous solubility of a drug is a crucial determinant of its dissolution rate, absorption and bioavailability. Drugs with relatively high intrinsic lipophilicity can be dissolved in appropriate mixtures of oils/lipids, surfactants, cosolvents which can rapidly form oil-in-water (o/w) fine emulsions when dispersed in aqueous phase under mild agitation or mixing. These isotropic self-emulsifying formulations or self-emulsifying drug delivery systems are effective for delivery of poorly soluble, lipophilic drugs by dispersing the drugs within fine oil droplets in emulsions and this solubilization of drugs can then improve its absorption, bioavailability and therapeutic efficacy. The present paper reviews the concept, design, formulation, characterization and applications of self-emulsifying formulations. Keywords: Self-Emulsifying Formulations, lipophilicity, emulsions