The Short Term Safety and Efficacy of Inhaled L-arginine in Patients With Cystic Fibrosis

Inclusion Criteria: * Diagnosis of CF as defined by two or more clinical features of CF and a documented sweat chloride concentration \> 60 mEq/L and/or two well characterized disease causing CFTR gene mutations * 14 years of age and older at enrollment * Clinically stable at enrollment * Ability to comply with medication use, study visits and study procedures * FEV1 % predicted \> 40% \< 80 % as calculated by reference equations Exclusion Criteria: * Respiratory culture positive for: B. cepacia complex within past year or at screening * Use of systemic corticosteroids within 30 days of screening * Use of intravenous antibiotics or oral quinolones within 14 days of screening * History of biliary cirrhosis, portal hypertension, or splenomegaly * Other major organ dysfunction * History of lung transplantation or currently on lung transplant list * Supplemental oxygen therapy * Oxygen saturation \< 95 % on room air * Positive pregnancy test at screening * Investigational drug use within 30 days of screening * History of alcohol, illicit drug or medication abuse within 1 year of screening * Acute respiratory symptoms * Inability to take any form of bronchodilator * Wheezing at the time of study