Polymer–mesoporous silica composites for drug release systems

The research describes systematic approach to the novel synthesis and formation of a potential organic-inorganic drug carriers. The poly(trimethylolpropane trimethacrylate) and polymer-silica composites based on SBA-3 or SBA-15 mesoporous silica were fabricated by the suspension-emulsion polymerization method in the form of small micrometric porous beads (specific surface area approx. 500 m2/g). The type of organic templates filling silica pores has proved to be crucial in the synthesis of the composites. The introduction of diclofenac sodium via solvent diffusion method into the polymer and composites resulted in the solid drug dispersions. The composites have greater effectiveness in the drug desorption (90% of the release) in comparison with the pure polymer (20% of the release after 7 h). Both, however, suffer from the burst effect. This downside can be overcome by functionalization of the solid drug dispersions with (3-aminopropyl)triethoxysilane. The functionalized solid drug dispersions do not desorb the diclofenac sodium in an acidic medium (the desorption rate is less than 6% during 2 h contact), which makes them attractive for oral multiparticulate formulations of modified release. The presented solids were characterized with modern analytical methods and the relation between the material structure and desorption rate were discussed.