UV SPECTRAL STRATEGIES FOR ANALYTICAL METHOD DEVELOPMENT OF MULTICOMPONENT DRUG FORMULATION

This research work aimed at the development and validation of three UV spectrophotometric methods, namely, Ratio Subtraction and Extended Ratio Subtraction (RS-ERS), Ratio Subtraction coupled with Constant Multiplication (RS-CM), and Ratio Subtraction coupled with Spectrum Subtraction (RS-SS) for the simultaneous estimation of Benidipine Hydrochloride (BEN) and Chlorthalidone (CHL) in their combined pharmaceutical dosage form. BEN was detected at 237 nm and CHL at 275 nm. For determination of CHL, BEN at 10 µg/mL was used as the divisor; for determination of BEN, CHL at 18.7 µg/mL was used as the divisor. The methods were validated in accordance with ICH Q2(R2) guidelines for linearity, specificity, accuracy, precision, robustness, LOD, and LOQ. The linearity was established in the concentration ranges of 4-12 µg/mL for BEN and 6.2-18.7 µg/mL for CHL, and good correlation coefficients (r² = 0.9996) were obtained for all methods. Precision studies demonstrated %RSD values below 2% for both intra-day and inter-day analysis, reflecting good repeatability and intermediate precision. The accuracy results were within the acceptable range of 98–102%. The developed methods were found to be robust with %RSD values below 2%. The methods showed adequate sensitivity with LOD and LOQ values of 0.29 µg/mL and 0.87 µg/mL for BEN and 1.10 µg/mL and 3.34 µg/mL for CHL, respectively. The assay of the commercial formulation yielded results within pharmacopeial specifications. The greenness and sustainability of the methods were evaluated using AGREE and ComplexGAPI tools.