Self-emulsifying Drug Delivery System: A Review

Abstract

Drug development in the past used to be initiated after the identification of most active molecule. However,
this approach leads to a number of drawbacks with the problems being that many molecules which are
put into development had poor physicochemical such as solubility and stability and biopharmaceutical
such as permeability and enzymatic stability properties, as a consequence of which about 40% of new
chemical entities fail to reach the market place. At present, a number of technologies are available to
deal with the poor solubility, dissolution rate, and bioavailability of insoluble drugs. However, much
attention has been focused on lipid-based formulations, with particular emphasis on self-emulsifying
drug delivery systems (SEDDSs). SEDDSs are defined as isotropic mixtures of natural or synthetic
oils, solid or liquid surfactants, or one or more hydrophilic solvents and cosolvents/surfactants. On mild
agitation followed by dilution in aqueous media, these systems can form fine oil-in-water emulsions
or microemulsions (self-micro-EDDS [SMEDDS]). Self-emulsifying formulations spread readily
in the gastrointestinal tract, the digestive motility of the stomach and intestine provides the agitation
necessary for self-emulsification. SEDDSs produce emulsification with a droplet size between 100 and
300 nm, while SMEDDSs form transparent microemulsions with a droplet size of <50 nm. SEDDSs are
physically stable formulations that are easy to manufacture. Thus, for lipophilic drug compounds that
exhibit dissolution rate-limited absorption, these systems may offer an improvement in the rate and the
extent of absorption.