A Robust HPLC Method for the Simultaneous Determination of Finerenone and Its Enantiomer Using AQbD

The enantiomeric purity of Finerenone (FIN), a novel therapeutic for chronic kidney disease (CKD), is a critical quality attribute for ensuring patient safety. This study reports the first chiral HPLC method for the simultaneous determination of FIN and its enantiomer, developed and validated using a rigorous analytical quality by design (AQbD) framework. The method employs a CHIRALPAK AD-H column with an isocratic mobile phase of n-hexane: ethanol (62:38, v/v). Optimized conditions provide excellent baseline resolution (Rₛ = 3.5) in under 10 min. The method was validated using accuracy profiles, demonstrating high performance with limits of quantification established at 340 μg mL^-1 for FIN and 0.40 μg mL^-1 for its 4R enantiomer. The AQbD approach successfully defined a robust method operable design region (MODR) to ensure consistent performance. Furthermore, a multimetric sustainability evaluation confirmed the method's favorable eco-profile, achieving a Grade Index (BAGI) score of 77.5 and Red-Green-Blue 12 (RGB12) score of 80.8. This work provides a reliable, robust, and eco-conscious analytical tool essential for the quality control of FIN formulations.