The experimental intervention was to take dornase alpha after and the placebo ZD6474 before performing the airway clearance techniques once daily for 14 days. The control intervention was to take dornase alpha before and the placebo after the airway clearance techniques for 14 days. The active ampoules contained 2.5 mg of dornase alpha in 2.5 mL. The placebo ampoules contained 2.0 mL of 0.9% saline. To preserve blinding, all ampoules were stored under refrigeration – a requirement of dornase alpha. Each participant was supplied

with two jet nebulisersa to be used for inhaling the trial solutions. The nebulisers were colour-coded to match the trial solution packaging, but were otherwise identical. Separate nebulisers were necessary because dornase alpha can be denatured by traces of other compounds in the nebuliser chamber. At the start of the trial, all nebuliser pumps were tested to ensure that they produced adequate flow rates (6–8 L/min) with sufficient driving pressures (10–12 pounds per square inch, 69–83 kPa). All participants received usual medical and allied health management by the Cystic Fibrosis Unit if required during the trial period, and were encouraged

to continue with their other usual therapies. Participants who were already taking bronchodilators were advised to inhale them before the inhalation of the first trial solution at each daily treatment session. Participants who were already taking

PLX3397 mw inhaled antibiotics were advised to inhale them after the inhalation of the second trial solution at each daily treatment session. Demographic and clinical data including age, gender, body mass index, bacterial colonisation of sputum, usual medication use, lung function, oxyhaemoglobin saturation, and quality of life were recorded at baseline (Day 0). On Day 1, participants received the blinded therapy under clinical supervision. Lung function was measured before and after each nebulisation and both before and after the physical airway clearance techniques to assess any acute changes during the intervention. Cumulative sputum weight was measured after each spirometry measurement. Subsequent doses were inhaled independently at home. On the first day of the second treatment arm (Day 15) the same measurements were performed. All outcome measures were recorded Oxalosuccinic acid at the start and end of the first 14-day period (Days 1 and 14) and at the start and end of the second 14-day period (Days 15 and 28), as presented in Figure 1. All measurements were performed by an investigator who was blinded to whether the participant was in the experimental or control arm of the study. Participants were also blinded throughout the study, including when they completed the quality of life questionnaires. Lung function was measured using a standard spirometerb according to American Thoracic Society guidelines (American Thoracic Society 1995).