Effect of Miglustat on the Nasal Potential Difference in Patients With Cystic Fibrosis Homozygous for the F508del Mutation

Inclusion Criteria: Inclusion criteria at screening visit (Visit 1): * Aged 18 years and older * Male or female * Women of childbearing potential must: * have a negative serum pregnancy test at Visit 1 * agree to use from Visit 1 until 3 months after the last study drug intake a reliable method of contraception * Male patients accepting for the duration of the study and for 3 months thereafter to use a condom * Homozygous for the F508del mutation as confirmed by genetic testing * Sweat chloride ≥ 60 mmol/L * Basal nasal potential difference (NPD) ≤ -30.0 mV (equal to or more electrically negative than -30.0 mV) and total chloride secretion (TCS) ≥ - 5.0 mV for at least one nostril. However, if it is possible to analyze both nostrils, the total chloride secretion (TCS) is to be ≥ - 5.0 mV (equal to or more electrically positive than - 5.0 mV) in both nostrils. * FEV1 ≥ 25% of predicted * Able to comply with all protocol requirements * Signed informed consent prior to any study-mandated procedure Inclusion criteria at randomization visit (Visit 2): * Women of child-bearing potential must have a negative urine pregnancy test * Basal nasal potential difference (NPD) ≤ - 30.0 mV (equal to or more electrically negative than - 30.0 mV) and total chloride secretion (TCS) ≥ - 5.0 mV for at least one nostril. However, if it is possible to analyze both nostrils, the total chloride secretion (TCS) is to be ≥ - 5.0 mV (equal to or more electrically positive than - 5.0 mV) in both…