Ivacaftor

Ivacaftor (VX-770, VX770) is a potent, orally bioavailable CFTR potentiator, increases G551D- and F508del CFTR-mediated Cl- secretion with EC50 of 100 nM; increases CFTR channel open probability (Po) in both the F508del processing mutation and the G551D gating mutation in recombinant cells, increases the Po of G551D CFTR by 6-fold, the Po of F508del- and wild-type CFTR by 5-fold and 2-fold, respectively; also potentiates CFTR-mediated Cl secretion in primary cultures of G551D/F508del HBE and F508del HBE; demonstrates potential for treatment of cystic fibrosis with certain mutations in CFTR gene (primarily the G551D mutation).Fibrosis Approved(In Vitro):Ivacaftor (10 μM) increases the PC secretion activity by 3-fold for ABCB4-G535D, 13.7-fold for ABCB4-G536R, 6.7-fold for ABCB4-S1076C, 9.4-fold for ABCB4-S1176L, and 5.7-fold for ABCB4-G1178S. Ivacaftor corrects the functional defect of ABCB4 mutants. Ivacaftor (10 μM) significantly increases CFTR activity in W1282X-expressing cells compared to R1162X CFTR cells. Ivacaftor shows no significant activity against 160 targets tested including the GABAA benzodiazepine receptor. Ivacaftor increases the chloride secretion with an EC50 of 0.236 ± 0.200 μM, a 10-fold shift in potency compared to the F508del HBEs. In recombinant cells, VX-770 increases CFTR channel open probability (Po) in both the F508del processing mutation and the G551D gating mutation. VX-770 increases forskolin-stimulated IT in temperature-corrected F508del-FRT cells by appr 6-fold with an EC50 of 25 nM.(In Vivo):Ivacaftor (1-200 mg/kg, p.o.) exhibits good oral bioavailability in rat.