Oral route has always been preferred route for formulators and has dominated over other routes of administrations. However this preferred route is limited to those drug molecules that are permeable across the gastric mucosa and are at least sparingly soluble. Unfortunately, approximately 40% of new chemical entities (NCEs) exhibit poor aqueous solubility and present a major challenge to the successful development and commercialization of new drug delivery system, because of their low bioavailability. Furthermore, oral delivery of numerous drugs is hindered due to their high hydrophobicity or lipophilicity. Lipophilic and less water-soluble therapeutic agents have decreased bioavailability, increased chance of food effect, incomplete release from the dosage form and a high inter- and intra-subject variability.
Self Micro-emulsifying Drug Delivery System (SMEDDS) is a novel approach to improve water solubility and bioavailability of drugs. SMEDDS are isotropic (one phase system) mixture of oil or modified oils, surfactants and co- surfactants, which form fine oil-in-water microemulsions when introduced into the aqueous phase of the GI tract under conditions of gentle agitation in vivo. SMEDDS is evaluated by various methods like visual assessment, droplet polarity and droplet size, dissolution test, charge of oil droplets, viscosity determination, in vitro diffusion study.
With further development of this technology, SMEDDS will continue to enable novel applications in drug delivery and solve problems associated with the oral delivery of poorly soluble drugs.
Table 4: Examples of Pharmaceutical Products formulated as Solid self emulsifying systems.
Thus SMEDDS are a promising approach to effectively tackle the problem of absorption and hence bioavailability of poorly soluble drugs.