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A randomized controlled trial of inhaled L-arginine in patients with cystic fibrosis
H Grasemann1, E Tullis, F Ratjen
1Division of Respiratory Medicine, Department of Pediatrics, the Hospital for Sick Children, University of Toronto, Toronto, Canada. hartmut.grasemann@sickkids.ca
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.
