An Integrated Quality by Design RP-UPLC Method for Lumacaftor and Ivacaftor in Human Plasma

Cystic fibrosis, a genetic disorder caused by mutations in the CFTR gene, is commonly treated using combination therapy with IVA and LUMA. Accurate quantification of these drugs in human plasma is essential for therapeutic monitoring; however, conventional analytical methods often lack sufficient sensitivity and robustness. In this study, a QbD-based RP-UPLC method was developed and validated for the simultaneous estimation of IVA and LUMA in human plasma. The primary objective was to achieve efficient separation of analytes from plasma interferences with reduced run time and consistent analytical performance. Chromatographic separation was carried out using a Waters Acquity UPLC system equipped with a CSH C18 column (100 mm × 2.1 mm, 1.8 μm). Method optimization was performed using a Central Composite Design model. The mobile phase is 0.01 N ammonium acetate and acetonitrile (60:40, v/v) at a flow rate of 0.3 mL/min, with the column maintained at 30°C. EMT was used as the internal standard, and detection was conducted at 260 nm. The retention times were 1.45, 1.77, and 1.99 min for EMT, IVA, and LUMA, respectively. The method is reliable, rapid and selective, exhibiting excellent linearity, precision, and accuracy, complying with USFDA guidelines.