This is a 5-part study of FDL176. Part 1 is a double blind, placebo-controlled, dose escalation study in healthy male participants. Part 2 is a single dose, open-label study in healthy male participants. Part 3 is a single dose, double blind, placebo-controlled study in healthy female participants. Part 4 is a randomised, double-blind, placebo-controlled, dose-escalation study in healthy male and female participants.Part 5 is a single dose, open-label study in male and female participants with CF.