Ivacaftor on January 31,2012. It is used to treat Cystic Fibrosis in 6 years or older. Ivacaftor is the first drug that treats an underlying cause of Cystic Fibrosis(CF), rather than the symptoms of the disease. CF is not curable, the treatment is focused on alleviation of symptoms and treatment of complications. Proposed Dosage: 150 mg twice daily (300 mg/day). Route of Administration: Oral Mechanism of action: Ivacaftor acts as a CFTR (Cystic Fibrosis Transmembrane Conductance Regulator). The CFTR