Self micro-emulsifying drug delivery system: formulation development and biopharmaceutical evaluation of lipophilic drugs.

Several methods are being employed to improve the oral bioavailability of lipophilic drugs like using inert lipid vehicles such as Oils, Surfactant dispersions, Self Microemulsifying Drug Delivery Systems (SMEDDS) and Liposomes. SMEDDS is formulated with the help of oil or suitable lipid materials, Surfactants and hydrophilic Co-surfactants. Mixture of above ingredients can be filled in a soft capsule and ingested. When the mixture comes in contact with gastrointestinal fluid it forms a stable O/W Microemulsion. A pseudo ternary phase diagram is used for identifying the efficient Self micro-emulsification region. SMEDDS can be formulated to give sustained release by use of inert polymers. When this polymer comes in contact with GI fluids, it forms gelled polymeric matrix, which releases the micro-emulsified active principle in a continuous and prolonged manner. Physical characterization of SMEDDS should be carried out by droplet size analysis and spontaneity of emulsification. The purpose of this review is to provide a brief out line of the formulation of SMEDDS, possible mode for improving bioavailability, fate and evaluation of the same.