Ivacaftor-d19 is intended for use as an internal standard for the quantification of ivacaftor by GC- or LC-MS. Ivacaftor is an orally bioavailable potentiator of the cystic fibrosis transmembrane conductance regulator (CFTR) that improves chloride transport. It increases the forskolin-induced CFTR-mediated epithelial current in cells expressing the G551D missense mutation associated with severe cystic fibrosis by approximately 4-fold (EC50 = 100 nM) but has no effect on current in the absence of forskolin. Ivacaftor increases chloride secretion in cultured human cystic fibrosis bronchial epithelial cells carrying the G551D mutation on one allele and the common ΔF508 processing mutation on the other allele. It binds CFTR directly and leads to CFTR channel opening via an ATP-independent mechanism. Formulations containing ivacaftor have been used in the treatment of cystic fibrosis in patients carrying one or more mutations in the CFTR gene.
