Electrospraying as a Means of Loading Itraconazole into Mesoporous Silica for Enhanced Dissolution

Abstract

Mesoporous silica particles (MSPs) have been investigated as potential carriers to increase the apparent solubility and dissolution rate of poorly water-soluble drugs by physically stabilising the amorphous nature of the loaded drug. In preparing such systems, it is recognized that the loading method has a critical impact on the physical state and performance of the drug. To date, there has been very limited investigation into the use of electrospraying for loading drugs into mesoporous silica. In this study, we further explore the use of this approach, in particular as a means of producing amorphous and high drug-loaded MSPs; the study includes an investigation of the effect of drug loading and MSP concentration on the formulation performance and process. A comparison with rotary evaporation, a more widely utilised loading technique, was conducted to assess the relative effectiveness of electrospraying. The physical state of the drug in the formulations was assessed using powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC). The drug release profiles were determined by a comparative in vitro drug release test. Electrospraying successfully produced formulations containing amorphous drug even at a high drug loading. In contrast, while itraconazole was present in amorphous form at the lower drug-loaded formulations produced by rotary evaporation, the drug was in the crystalline state at the higher loadings. The percentage of drug released was enhanced up to ten times compared to that of pure itraconazole for all the formulations apart from the highest loaded (crystalline) formulation prepared by rotary evaporation. Supersaturation for at least six hours was maintained by the formulations loaded with up to 30 mg/mL itraconazole produced by electrospraying. Overall, the results of this study demonstrate that electrospraying is capable of producing amorphous drug-loaded MSPs at high loadings, with associated favourable release characteristics. A comparison with the standard rotary evaporation approach indicates that electrospraying may be more effective for the production of higher loadings of amorphous material.