Graphical abstract
Dry powder inhalation (DPI) formulations containing ciprofloxacin hydrochloride (CIP) as a model drug were prepared by spray-drying in the presence of different ethanol concentrations. The role of ethanol on the habit and aerodynamics of the DPI samples was examined in detail. The roughness, depth and width of the dimples were uniquely expressed. A new correlation was determined between the mass median aerodynamic diameter (MMAD)/D (0.5) ratio and cohesion work (Wc). DPI formulation containing 30% ethanol in the stock solution had the best
in vitro
aerodynamic results.