Quality-by-Design-Driven RP-HPLC Method Development and Validation for Impurity Analysis of Elexacaftor, a Cystic Fibrosis Drug, with LC-MS/MS-Based Degradant Identification

The development and validation of an analytical technique based on RP-HPLC for the determination of impurities in Elexacaftor (ELX). Using a straightforward and stability-indicating HPLC technique, six known contaminants were precisely assessed with the right resolutions and peak forms. In a number of separation studies, the chromatographic separation was accomplished using an XBridge Shield RP 18, 150 mm × 4.6 mm, 3.5 μm column. The mobile phases consisted of methanol, acetonitrile, 2-propanol, and 10 mM potassium dihydrogen orthophosphate buffer used for the analysis. The gradient elution process took 90 min to complete, and the column temperature was 27 °C. Photodiode array optimization was accomplished at 220 nm with a 0.7 mL/min flow rate. The developed procedure was validated following ICH requirements and discovered to be robust, linear, accurate, specific, selective, and exact. The method range extended from LOQ to ∼0.45% for impurities and LOQ to ∼120% for the Elexacaftor drug substance. The method robustness was established by utilizing the DoEs in the part of the QbD concept. The method's stability was evaluated under diverse conditions including acid and base hydrolysis, oxidative and water hydrolysis, and thermal and photolytic degradation and was helpful for process development as well as quality checks in bulk drug manufacturing.