Mesoporous silicas for incorporation and reléase of drugs = Silicas mesoporosas para la incorporación y liberación de fármacos

For drug delivery applications, it is desirable that the drug is released with a maintained therapeutic level, at a specific site and with a specific rate in the body. To achieve this, drug molecules have to be encapsulated in a carrier. Ordered mesoporous silicas (OMSs) have been suggested to be used as a reservoir for drug molecules, since they have mesoporous structure, biocompatibility, high loading capacity, efficient encapsulation of cargo molecules, high surface areas and tunable pore sizes and volumes. OMSs have shown to enhance the dissolution rate of poorly water soluble drugs. At least 40% of drugs developed exhibit poor water solubility, which limits drug dissolution rate, reducing drug bioavailability. A method for improving the dissolution rate is to increase its surface area in contact with the dissolution media, which can be achieved by loading the drug onto a high surface area carrier as that of OMSs. The aim of this work was to evaluate different amorphous silicas for incorporation of a water insoluble antifungal agent, Clotrimazole, by using scCO2 as impregnation process. Clotrimazole was incorporated on three different silicas (Formac, SBA-15 and SYLOID® AL-1 FP). It was possible to determine the relationship between pore volume, size and morphology and surface area with the incorporation degree. An important observations is that OMSs are much more efficient at incorporating drugs than the commercial formulation Syloid® AL-1 FP, which indicates that OMSs are a promising carrier to achieve enhanced oral bioavailability for drugs with low water solubility. Moreover, OMSs showed to be stabilizers for amorphous clotrimazole, which represents an interesting approach in the dissolution enhancement