Cystic fibrosis is caused by any one of several defects in a protein, cystic fibrosis transmembrane conductance regulator, which regulates fluid flow within cells and affects the components of sweat, digestive fluids, and mucus. The defect, which is caused by a mutation in the individual's DNA, can be in any of several locations along the protein, each of which interferes with a different function of the protein. One mutation, G551D, lets the CFTR protein reach the epithelial cell surface, but doesn't let it transport chloride through the ion channel. Ivacaftor is a potentiator of the CFTR protein. The CFTR protein is a chloride channel present at the surface of epithelial cells in multiple organs. Ivacaftor facilitates increased chloride transport by potentiating the channel-open probability (or gating) of the G551D-CFTR protein.
Ivacaftor is a cystic fibrosis transmembrane conductance regulator (CFTR). In patients with the G551D mutation, Kalydeco, a pill taken two times a day with fat-containing food, helps the protein made by the CFTR gene function better and as a result, improves lung function and other aspects of CF such as increasing weight gain.
Ivacaftor is extensively metabolized in humans. In vitro and clinical studies indicate that ivacaftor is primarily metabolized by CYP3A. M1 and M6 are the two major metabolites of ivacaftor in humans. M1 has approximately one-sixth the potency of ivacaftor and is considered pharmacologically active. M6 has less than one-fiftieth the potency of ivacaftor and is not considered pharmacologically active.