Self Micro Emulsifying Drug Delivery System: An Approach to Enhance an Oral Bioavailability of Lipophilic Drugs

Most of the drugs are being discovered are lipophillic in nature and have poor aqueous solubility, thereby posing problems in their formulation into delivery systems. Due to their low aqueous solubility and low permeability, dissolution and/or release rate from the delivery system forms the rate limiting step in their absorption and systemic availability. Self microemulsifying drug delivery system is one method for improving oral bioavailability. SMEDDS composed of oil, surfactant, co-surfactant, solvents, and co-solvents. This review describes the advantages, disadvantages, formulation aspects and ternary phase diagram construction for SMEDDS. It also explains mechanism of self emulsification and characterization of SMEDDS. Some of the marketed preparations of SMEDDS are listed in detail.