(137a) Dissolution-Rate Enhancement of Fenofibrate by Adsorption Onto Silica Using Supercritical Carbon Dioxide

Dissolution rate of a poorly-water-soluble lipid-regulating drug, fenofibrate, is increased by adsorbing the drug onto silica. The adsorption is achieved by first dissolving the drug in supercritical carbon dioxide and then depressurizing the solution on silica. Loadings of up to 27.5 wt% of fenofibrate onto silica are obtained. Since solvents are not used in the loading process, the fenofibrate/silica formulation is free of any residual solvent, and carbon dioxide freely leaves upon depressurization. The formulation was characterized using infrared spectroscopy, ultraviolet spectroscopy, x-ray diffraction, differential scanning calorimetry and scanning electron microscopy. Based on in-vitro dissolution study, a significant increase in the dissolution rate (~80% drug release in 20 minutes) of drug-silica formulation has been observed as compared to micronized fenofibrate (~20% drug release in 20 minutes). The high dissolution rate of drug-silica formulation can be attributed to increase in the surface area and decrease in the crystallinity of drug after adsorption onto silica. Two different formulations are compared: (A) amorphous fenofibrate/silica, and (B) slightly-crystalline fenofibrate/silica. The second formulation is found to be stable on storage.