[Preparation and release behaviour of mesoporous silica/ethylcellulose sustained-release mini-matrix].

Hot-melt extrusion was applied to prepare mesoporous silica/ethylcellulose mini-matrix for sustained release, and fenofibrate was used as a model drug, ethylcellulose and xanthan gum were chosen as sustained-release agent and releasing moderator, respectively. This novel matrix obtained the controlled release ability by combining mesoporous silica drug delivery system and hot-melt extrusion technology. And mesoporous silica particle (SBA-15) was chosen as drug carrier to increase the dissolution rate of fenofibrate in this martix. Scanning electron microscope, transmission electron microscope, small angle X-ray powder diffraction and N2 adsorption-desorption were introduced to determine the particle morphology, particle size and pore structure of the synthesized SBA-15. The results showed that SBA-15 had a very high Brunauer-Emmett-Teller specific surface area, a narrow pore size distribution, large pore volume and a ordered two-dimensional hexagonal structure of p6mm symmetry. Differential scanning calorimetry and X-ray powder diffraction results demonstrated that fenofibrate dispersed in an amorphous state inside the pores of the mesoporous silica which contributed to the improvement in the dissolution rate. The drug release of mini-matrices was influenced by ethylcellulose viscosity grades and xanthan gum concentration, which increased with the increasing of xanthan gum concentration and decreasing of ethylcellulose viscosity. Mini-matrix containing 22% xanthan gum exhibited a good sustained release performance, and the drug release behavior followed the first-order kinetics.

[Improving the dissolution rate of poorly water-soluble resveratrol by the ordered mesoporous silica].

The aim of this study is to synthesize the ordered mesoporous silica (OMS) as drug carrier to improve release property of insoluble drug and investigate the dissolution profile of insoluble drug from the porous carrier. The OMS was obtained by using cetyltrimethyl ammonium bromide as the template and resveratrol was selected as the model drug. The resveratrol-loaded OMS (Res-OMS) were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption, X-ray diffraction (XRD) and FT-IR spectroscopy. In vitro drug release behavior was also investigated. It was found that the synthesized OMS showed a large surface area, a narrow pore size distribution and an important mesoporosity associated to hexagonally organized channels. Compared with physical mixture and crystalline powder, resveratrol was in amorphous or molecular form after loading into OMS. The release rate ofresveratrol from drug-loaded OMS was significantly increased suggesting the great potential application of OMS for the formulation of poorly soluble drugs.