Itraconazole formulation studies of the melt-extrusion process with mixture design

Itraconazole is a poorly water soluble compound. One method to increase the aqueous solubility of itraconazole is through formation of a solid dispersion. The purpose of this study is to develop a 40% w/w itraconazole formulation through solid dispersion formation, using hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and hydroxypropylmethyl-cellulose (HPMC) as mixture components. The solid dispersion was obtained by melt-extrusion using a twin-screw corotating melt extruder. A D-optimal mixture design was applied for the development of the optimal itraconazole formulation. The itraconazole fraction varied between 20% w/w and 50% w/w in the mixture design and the HPMC and HP-beta-CD fractions varied between 10% w/w and 60% w/w. The itraconazole formulation was optimized by producing clear extrudates, minimizing the torque, and maximizing the glass transition temperature and the apparent itraconazole solubility in 0.1 N HCl. Regression models were developed for the torque, glass transition temperature, and apparent solubility of itraconazole. High itraconazole fraction in the mixture promoted a better melt processing (minimizes torque). High HPMC fraction (>33% w/w) resulted in clear extrudates, indicating a solid dispersion and resulted in high glass transition temperature of the melt. High HP-beta-CD fraction resulted in increased apparent itraconazole solubility in 0.1 N HCl. The optimal itraconazole formulation consisted of 45% w/w HPMC and 15% HP-beta-CD w/w.