NCT00928135.

Methods	RCT. Parallel design. Duration; 14 days. Triple‐blind (participant, care provider, investigator).
Participants	Estimated enrolment: 60 participants. Both genders eligible. Inclusion criteria: diagnosed with CF (medical record evidence of CFTR mutation or sweat chloride test or nasal voltage difference, and 1 or more clinical findings of CF); 12 years or older; FEV1 > 30% predicted (within the last 14 days and oxygen saturation > 90% on FiO2 ≤ 50%); admitted for an exacerbation; use of effective contraception in women; written informed consent. Exclusion criteria: pregnancy; history of asthma based on methacholine challenge or bronchial hyper‐responsiveness on PFT; haemoptysis more than 60 mL within the last 30 days; use of any investigational study drug within the last 30 days; initiation of hypertonic saline within the last 30 days; a serum creatinine 2 mg/dL or more; active malignancy in the last year; antibiotics for CF exacerbation as an outpatient in the last 2 weeks; Burkholderia cepacia colonisation; waiting list for lung transplant; lack of FEV1 data from the last 14 days; previous participation in this study.
Interventions	Intervention: aerosolized 7% HS (5 mL) 2x daily. Control: 15% xylitol (5 mL) 2x daily.
Outcomes	Primary outcomes FEV1 (change from baseline). Adverse events. Respiratory symptom score. Secondary outcomes Density of colonisation per g of sputum. Time to next exacerbation. Sputum cytokines. CFQ‐R.
Notes	Principal Investigator: Joseph Zabner, M.D. Study Director: Lakshmi Durairaj, M.D. Study Chair: Jan L Launspach, R.N., CCRC. Study Start Date : June 2009. Estimated Primary Completion Date : January 2018. Estimated Study Completion Date : January 2018.