Solid-state loading of organic molecular materials within mesoporous silica matrix: Application to ibuprofen

Mesoporous silica carriers have recently gained interest in the pharmaceutical domain because of their potential to significantly increase the solubility of poorly water-soluble drugs, by adsorbing the active molecule in an amorphous and relatively stable state. However, the use of organic solvents for drug loading and the limited loading capacity are real drawbacks in the context of therapeutic use. The present work shows that co-milling of porous SBA-15 matrix with the drug makes it possible the drug loading without significant damage for the structure of the matrix, enhancing thereby the capacity of loading to almost 40 wt%. Combining calorimetric, thermogravimetric, and low-frequency Raman investigations has allowed us to determine optimum conditions of loading, and to analyze the physical state, the molecular mobility and the phase transformations of the confined drug upon heating. It was shown that the physical state of ibuprofen (IBP) confined to silica carriers was amorphous between temperatures T-g and T-m of the bulk form of IBP.