The primary endpoint was the within-subject change from baseline in total chloride transport as measured by NPD, after the Chloride-free+isoproterenol solution (Cl-free+iso), and was based on the average measurements of both nostrils. To provide baseline stability, baseline was defined as the average of the two most recent pre-dose values, where each pre-dose value was the average of two nostrils. A negative change from baseline of Cl-free+iso shows an improvement.

Number of subjects experiencing at least one treatment emergent adverse events (TEAEs)

Assessment of severity of treatment emergent adverse events (TEAEs). Severity is graded using the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events Modified for CF (CTCAE v4.03). For events not present in this listing the following grading was applied: Mild: Asymptomatic or mild symptoms; clinical or diagnostic observations only; intervention not indicated; Moderate: Minimal, local, or noninvasive intervention indicated; discomfort sufficient to reduce or interfere with daily activities; Severe: Medically significant but not immediately life-threatening; hospitalization or prolongation of hospitalization may be indicated; disabling; limits self-care with significant interference with daily activities; incapacitating with inability to perform self care activities of daily living; Life-threatening: Urgent intervention indicated; immediate risk of death.

DLT's were defined as an allergic reaction, acute bronchospasm or acute AEs of interest requiring (immediate) medical intervention.