Cortisol controlled release by mesoporous silica.

In this study four types of SBAs were synthesized and then impregnated with hydrocortisone. One is a straight SBA-15, obtained using Pluronics P123 as structuring agent; two others were modified using 1,3,5-trimethylbenzene as additive, and the fourth one was prepared using sodium iodide as additive. Three of these have in common a p6 mm symmetry with nanotubes packed hexagonally, yet they differ in their functional groups. The fourth sample is basically disordered. The drug release kinetics showed two stages: a fast-rate early stage dominated by the controlled release of the hydrocortisone adsorbed in the macropores of the reservoir, followed by a slow-rate delivery that we assume is controlled by the hydrocortisone diffusion through the nanopores. It is shown that the release kinetics can be strongly influenced by using different co-additives.