The Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene codes the function of the chloride ion channel which is at the surface of some epithelial cells. Mutations to the CFTR gene causes defects in chloride transport that leads to an alteration of epithelial fluid transport in the lung and other organs, which causes cystic fibrosis. CFTR potentiators repair defects in chloride transport, and are used to treat cystic fibrosis patients with a specific gene mutation. CFTR combinations drugs are when more than one CFTR potentiator is combined into one drug for increased efficacy.