Within the CF lung, P. aeruginosa grows as a biotic biofilm in association with airway epithelial cells and mucous plaques. This environment has an acidic pH and low oxygen tension with many bacteria subsisting through denitrification (both conditions where traditional antibiotics are less effective). Because biotic biofilms can be up to 500-fold more resistant than biofilms grown on abiotic surfaces, with support from our CF Research Development Program (RDP) Cores, we showed that nitrite prevents biofilm formation on the surface of primary CF airway epithelial cells. Moreover, nitrite dose-dependently potentiates the effects of colistin sulfate in liquid culture, and in biotic biofilms on airway epithelial cells. These data support the hypothesis that nebulized sodium nitrite will inhibit growth of Pseudomonas aeruginosa in CF airways, and identify a potential therapeutic benefit for nitrite alone and cooperatively with colistin as a novel therapy to inhibit P. aeruginosa in CF airways. Nebulized nitrite has been through extensive animal toxicology, and is well tolerated by subjects with pulmonary arterial hypertension where it is being studied as a pulmonary vasodilator.