Study of Denufosol Tetrasodium in Patients With Cystic Fibrosis Lung Disease

Inclusion Criteria: * Have confirmed diagnosis of CF * Have an FEV1 greater than or equal to 60% or less than or equal to 90% of predicted normal * Have oxygen saturation greater than or equal to 90% on room air * Be clinically stable with no evidence of acute upper or lower respiratory tract infection or current pulmonary exacerbation * Be able to reproducibly perform spirometry maneuvers Exclusion Criteria: * Have changed their physiotherapy technique or schedule within 7 days prior to screening * Have clinically significant comorbidities * Using prior and concurrent medications according to the protocol