A randomized controlled trial of inhaled l -Arginine in patients with cystic fibrosis

Abstract Background Cystic fibrosis (CF) airways are nitric oxide (NO) deficient. We studied safety and efficacy of repeated inhalations of nebulized l -arginine, the substrate for NO synthase (NOS), in patients with CF. Methods Double-blind, randomized, placebo-controlled crossover treatment trial of twice daily inhalation of 500 mg l -arginine for two weeks compared to inhalation of saline in 19 CF patients (ClinicalTrials.gov Identifier: NCT00405665 ). Results l -Arginine inhalation was well tolerated and resulted in a significant increase in exhaled NO. FEV1 increased by an average of 56 ml compared to − 8 ml after saline solution; but this difference did not reach statistical significance. Sputum concentrations of l -ornithine, the product of arginase activity, increased significantly while the l -ornithine derived polyamines did not. There was no change in inflammatory markers in sputum. Conclusion Repeated inhalation of l -arginine in CF patients was safe and well tolerated. Inhaled l -arginine increased NO production without evidence for changes in airway inflammation.