The Study Of Daidzein Self-Microemulsifying Drug Delivery System

The oral delivery of hydrophobic drugs presents a major challe nge because of the low aqueous solubility of such compounds, which leads to poor oral bioavailability. Self-microemulsifying drug delivery systems (SMEDDS), which are isotropic mixtures of oils, surfactants and/or co-surfactants, can be used for the design of formulation in order to improve the oral absorption of lipophilic drug compounds. In our research, daidzein (DZ) SMEDDS was prepared.In this study, the equilibrium solubility of DZ in different oils and surfactants was determined by UV method, and the emulsifying efficiency was used to select compatible oil and surfactant. Ethylic oleate was chosen as oil phase. OP was used as surfactant, and a rapid dispersion and uniform drops of self-microemulsifying system was obtained. The phase diagrams of emulsifying agent, oil phase and aqueous phase were drawn to determine the microemulsion area. With the amount of oil phase and Km(Km=weight ratio of ethylic oleate to OP) as independent variables, the optimized formulation was determined by central composite design-response surface methodology. The response variables were emulsifying time, absorption of emulsion and drug content. The optimized formulation was ethylic oleate 20%, OP 64%, PEG 400 16%. The processing factors that affected the self-microemulsifying ability of SMEDDS had been studied. The dainzein SMEDDS was obtained by stirring by a magnetic stirrer at the speed of 300 r/min for 20 min at 37℃. It indicated that the dissolution speed of daidzein SMEDDS was obvious enhanced compared with the pure daidzein by determining drug release in vitro.SMEDDS can increase the stability, the equilibrium solubility and bioavailability of poorly soluble drugs. So it is a potential drug delivery system.