Efficacy and Safety of Inhaled Nitric Oxide (NO) in Cystic Fibrosis (CF) Patients

Inclusion Criteria: 1. Confirmed diagnosis of Cystic Fibrosis based on the following criteria: * positive sweat chloride 60 mEq/liter (by pilocarpine iontophoresis); and/or * a genotype with two identifiable mutations consistent with CF 2. Presence of Pseudomonas aeruginosa, Staphylococcus aureus or Stenotrophomonas maltophilia in the screening sputum culture. 3. Chronic microbial lung colonization (≥6 months) with presence of Pseudomonas aeruginosa, Staphylococcus aureus or Stenotrophomonas maltophilia in at least two (2) sputum cultures in the past year (the screening culture can count as one of the two positive cultures). 4. Ongoing chronic inhaled antibiotic therapy for at least 3 months prior to (screening or baseline). • For subjects on cycled therapy, at least 2 cycles of drug need to have been completed prior to baseline. 5. Willing to be off of inhaled antibiotic therapy from Day 1 to Day 15 6. Male or female subjects ≥18 years 7. FEV1 \<85% and \>35% at screening and baseline 8. SaO2 \>90% on room air at screening and baseline 9. Clinically stable with no significant changes in health status within 14 days prior to Baseline 10. Written Informed Consent and HIPAA authorization 11. Non-smoker for at least 6 months prior to screening and agrees not to smoke during the study 12. Chest x-ray within the last six (6) months. If none, a chest x-ray is required before randomization. 13. Willing and able to comply with the treatment schedule and procedures. Exclusion Criteria: 1. Initiation of any new chronic therapy (e.g., ibuprofen, Pulmozyme®, hypertonic saline, azithromycin, TOBI®, Cayston®) within 4 weeks prior to screening. 2. Use of antibiotics \[oral, intravenous (iv), and/or inhaled\] for acute respiratory symptoms within 2 weeks prior to baseline. 3. Significant hemoptysis within 30 days prior to screening (≥5 mL of blood in one coughing episode or \>30 mL of blood in a 24 hour period) 4. History of colonization with nontuberculosis mycobacterium in sputum culture. The investigator can be guided by the following suggested criteria for a subject to be considered free of colonization: * Two respiratory tract cultures negative for NTM in the last year, with no subsequent positive cultures; and * these 2 respiratory cultures must be separated by at least 3 months; and * one of these two cultures has to have been obtained within the last 6 months 5. Cardiac (left heart) insufficiency (defined as LVEF \<35%) at screening 6. Use of a nitric oxide donor agent such as nitroglycerin or drugs known to increase methemoglobin such as lidocaine, prilocaine, benzocaine or dapsone at screening 7. Any of the following abnormal lab values at Screening: * Hemoglobin \< 10 g/dl * Methemoglobn \>3% * Platelet count \<100,000/mm3 * Prothrombin time international ratio (INR) \> 1.5 * Abnormal liver function defined as any two of the following: * ALT \>3 x ULN * AST \>3 x ULN * ALP \> 3 x ULN * GGT \> 3 x ULN * Abnormal liver function defined as: * ALT \>5 x ULN * AST \>5 x ULN * Abnormal renal function defined as: * Calculated Creatinine Clearance \< 50 mL (as calculated by Cockcroft/Gault) 8. For women of child bearing potential: * positive pregnancy test at screening or * lactating or * unwilling to practice a medically acceptable form of contraception from screening to Day 36 (acceptable forms of contraception: abstinence, hormonal birth control, intrauterine device, or barrier method plus a spermicidal agent) 9. Use of an investigational drug within 30 days prior to screening 10. Intravenous or oral steroids in the 14 days prior to screening 11. Current use of inhaled steroids \>500 micrograms twice daily of Fluticasone or equivalent in the 30 days prior to screening 12. Use of supplemental oxygen (daytime or nocturnal) in the 7 days prior to screening 13. Any condition that the Investigator believes would interfere with the intent of this study or would make participation not in the best interest of the subject