A composition for pulmonary administration comprises a fluoroquinolonebetaine, such as ciprofloxacin betaine,and an excipient. In one version, the particles have a mass median aerodynamicdiameter from about 1 µm to about 5 µm, and thefluoroquinolone has a half life in the lungs of at least 1.5 hours. Thecomposition is useful in treating an endobronchial infection,such as Pseudomonas aeruginosa, and is particularly useful in treating cysticfibrosis.
