Influences of material characteristics on ibuprofen drug loading and release profiles from ordered micro- and mesoporous silica matrices

A series of mesoscopically ordered silicas with different pore sizes, pore connectivity, and pore geometry have been studied as carrier matrices for controlled drug delivery systems. Ibuprofen was used as a model drug, and the release processes were monitored under in vitro conditions. The adsorption of ibuprofen from hexane was shown to be of Langmuir type in all cases, and the degree of drug loading was dependent on the specific surface area and the pore diameter of the host matrix. The release process is found to be mainly diffusion controlled, but clear differences were observed between the studied materials, which we mainly ascribe to differences in the pore connectivity and pore geometry of the materials, and the aqueous stability of the matrix. The studied nanostructured silicas display a high degree of drug loading, and, depending on the host material, a controlled drug release can be provided for time periods varying from hours to weeks.