Preparation of itraconazole/HP-β-CD inclusion complexes using supercritical aerosol solvent extraction system and their dissolution characteristics

Abstract

The purpose of this study was to investigate the feasibility of a supercritical fluid process, called aerosol solvent extraction system (ASES), for producing solid-state inclusion complexes of itraconazole (ITR) with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD). ITR was complexed with HP-β-CD at temperatures of 35–55 °C, pressures of 83–140 bar, CO 2 densities of 0.498–0.801 g/cm 3, and solution concentrations of 1–5% (w/v). The ASES-processed inclusion complex powders were observed to consist of agglomerates of very fine (100–500 nm) particles. From the experimental results of X-ray diffraction and differential scanning calorimetry, it was found that ITR intermolecularly interacted with the HP-β-CD cavity, resulting in the formation of inclusion complex. Furthermore, the ASES-processed ITR/HP-β-CD powders showed a significant enhancement in the ITR solubility (up to 753.6 μg/mL) in an aqueous medium of pH 1.2. The aqueous solubility of ITR increased with pressure at a constant temperature, and we could obtain a relatively high solubility of 341 μg/mL at 140 bar and 35 °C. In a solution concentration range of 1–5% (w/v), the solubility increased with decreasing concentration, yielding 289–407 μg/mL. When the molar ratio of ITR to HP-β-CD was varied from 1:1 to 1:3, the ITR solubility increased with HP-β-CD content, giving a value of 753.6 μg/mL for the 1:3 ratio. For the ASES-processed ITR/HP-β-CD powders, the percent dissolution of ITR also increased considerably and about 90% of ITR was dissolved within 5–10 min.