Cystic Fibrosis (CF) is a rare disease affecting 70000 people worldwide. CF patients are particularly susceptible to pulmonary infections caused mainly by bacterial pathogens such as Pseudomonas aeruginosa (PA). To manage chronic exacerbation, antibiotic for inhalation is required. The approved treatment is represented by inhalation of tobramycin. However, other aminoglycosides are objects of investigation. The aim of this work was to study in vitro the aerodynamic behaviour of an amikacin sulphate liquid solution after nebulization and an amikacin dry powder (AMK/NaST) after aerosolization from a Dry Powder Inhaler (DPI). AMK/NaST was prepared using a proprietary spray drying technology to construct a powder to inhale having high content of drug and respirability. AMK/NaST powder was characterized in term of drug loading, morphology and median volume diameter. The aerodynamic behaviour of an amikacin sulphate liquid solution and AMK/NaST was assessed. Amikacin solution for injection (500 mg) was nebulized with a Pari LC plus cup. AMK/NaST powder was loaded in the DPI device at the labelled dose of 94 mg of amikacin base. The fine particle dose of amikacin was similar comparing the two products (46.1 mg and 47.9 mg for amikacin solution and amikacin dry powder, respectively). The data indicate that 94 mg of amikacin base as dry powder afford a respirable dose equivalent, than one obtained by nebulizing a solution for injection containing 500 mg.