Comparison of fenofibrate-mesoporous silica drug-loading processes for enhanced drug delivery

Loading a poorly water-soluble drug onto a high surface area carrier such as mesoporous silica (SBA-15) can increase the drug's dissolution rate and oral bioavailability. The loading method can influence subsequent drug properties including solid state structure and release rate. The objective of this research was to compare several loading processes in terms of drug distribution throughout the mesoporous silica matrix, drug solid state form and drug release properties. A model poorly water-soluble drug fenofibrate was loaded onto SBA-15 using; (i) physical mixing, (ii) melt, (iii) solvent impregnation, (iv) liquid CO₂ and (v) supercritical CO₂ methods. Physical mixing resulted in heterogeneous drug-loading, with no evidence of drug in the mesopores and the retention of the drug in its crystalline state. The other loading processes yielded more homogeneous drug-loading; the drug was deposited into the mesopores of the SBA-15 and was non-crystalline. All the processing methods resulted in enhanced drug release compared to the unprocessed drug with the impregnation, liquid and SC-CO₂ producing the greatest increase at t=30 min.