Optimization and scaling-up of ITZ-based dry powders for inhalation

Dry powders for inhalation with amorphous itraconazole (ITZ) dispersed in a hydrophilic matrix were previously obtained by the spray-drying technique. This gave interesting aerodynamic and dissolution characteristics leading to promising lung pharmacokinetic and prophylaxis efficacy in a preclinical model of invasive pulmonary aspergillosis. The spray-drying allows dry powder to be obtained in a one-step process; nonetheless, the scale-up still presents a challenge in maintaining the main particle characteristics. This study aimed to investigate the feasibility of obtaining similar powder characteristics from concentrated solutions using laboratory-scale and pilot-scale spray dryer equipment. ITZ was solubilized in a solvent mixture (ethanol/ethyl acetate/water mixture 40:40:20 v/v/v) in mannitol solutions or suspensions. These mixtures were spray dried at laboratory scale to produce a solid dispersion for inhalation (SDI) containing amorphous ITZ dispersed in a mannitol matrix. A solution of 35% (So1) w/w ITZ was chosen to evaluate the scale-up process. This formulation was chosen for its high yield (60%), its amorphous ITZ content (100%), its good aerodynamic behavior (fine particle fraction - FPF = 33± 2%) and its increased dissolution profile compared to bulk ITZ. The scale-up process showed pilot-scale dry powders with a higher yield than lab-scale dry powders and similar aerodynamic performance and equivalent dissolution profiles. Moreover, all SDIs displayed improved release kinetics in comparison with bulk ITZ. Despite the slight differences between lab- and pilot-scale SDIs, this study shows that the scaling-up process allowed interesting ITZ-based SDIs to be obtained, in order to achieve pilot-scale production.

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