Drug delivery devices based on macroporous silica spheres

A new kind of silica materials was proposed as carriers for drug delivery. The materials are characterized by the presence of hierarchical macro/mesopores, penetrable macropores and large pore volumes. The unique structure renders them ideal carriers for efficient and sufficient loading of drugs to establish controlled delivery systems. A series of such materials were synthesized and derivatized with octyl or octadecyl to investigate their drug delivery behavior. Nimodipine, as a model drug, was entrapped into the carriers by repeated soaking, filtration and evaporation. It is found that the drug-loading amount increased with increasing mesopore sizes of the carriers. The loading amount can reach as high as 350 wt% (drug/carrier). The in vitro release studies demonstrate that both enhanced release and sustained release can be achieved on the proposed materials. Moreover, the release speed can be controlled by the macropore sizes and surface characteristics of the materials.