Development of dry salbutamol sulfate powder with high inhalation performance independent of inhalation patterns

While dry powder inhalations are commonly used to treat pulmonary diseases, their clinical performance depends on patient inspiratory flow patterns. The purpose of this study was to develop a new powder with high and stable therapeutic performance for various patients. We applied the supercritical antisolvent (SCF) method to salbutamol sulfate (SS) to prepare a bulky SS particle (SS-SCF). Tests of in vitro inhalation performance with a human inspiratory flow simulator revealed SS-SCF to be less susceptible to inspiratory flow patterns than milled SS. When inspired, the unique structure seemed to be broken resulting in small fragments that could be delivered to the lungs. However, stability tests under physical stress showed tolerance for transportation and handling. In addition, optimization of the concentration of the SS solution applied to SCF method improved the in vitro inhalation performance of SS-SCF. These results indicated that a unique bulky SS powder prepared by the SCF method was useful for dry powder inhalation.