Nanostructured silica-based drug delivery vehicles for hydrophobic and moisture sensitive drugs

Facile and robust fabrication methodologies of complex materials with high added value for controlled drug delivery systems are highly sought-after in the pharmaceutical industry. Here, we have relied on the use of supercritical fluids for the matrix synthesis as well as for the drug impregnation process. As a model system of a hydrophobic and moisture sensitive active agent, triflusal was impregnated in different aerogel and polymeric matrices using supercritical CO2. In vitro release profiles of drug carriers consisting of SiO2 aerogels as mesoporous monoliths and as microporous nanospheres loaded with triflusal are reported and compared to a more conventional polymeric system (PMMA). Silica-based matrices are found to prevent the hydrolization of the active ingredient more efficiently than the polymeric matrix and displayed much faster release kinetics. Moreover, the triflusal is dispersed in a molecular form inside the silica-based materials. Such features are considered of great interest to enhance the bioavailability of low solubility drugs.

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► Triflusal can be impregnated using supercritical CO2 in silica aerogel type materials and PMMA matrices.
► Silica aerogel-based matrices stabilize the drug in molecular form.
► Carboxylic H-bonding was determined to be the most feasible conformation for triflusal adsorbed in these matrices.
► Silica aerogels act as a moisture protection barrier for triflusal when compared with PMMA.
► In vitro studies showed a sustained release in the polymer, while a bioavailability increase was obtained for aerogels.