Analytical Method Development and Validation of Univariate Spectrophotometric Methods for Quantifying Binary Drug Combination in Hypertensive Care

The objective of present research work was to develop a novel, precise, and accurate UV spectrophotometric method based on four approaches: Ratio Subtraction Coupled with Extended Ratio Subtraction Method (RS-ERSM), Ratio Subtraction Coupled with Constant Multiplication Method (RS-CM), Ratio subtraction coupled with Spectrum Subtraction (RS-SS) and the Absorption Factor method (AFM) for simultaneous estimation of Azelnidipine and Olmesartan medoxomil in fixed dose combination. The method was validated according to ICH guideline Q2 (R2). For RS-ERSM, RS-CM and RS-SS, the absorbance of Azelnidipine was measured at 258.8nm, and that of Olmesartan medoxomil was measured at 255nm. For AFM, Azelnidipine was measured at 342.2nm, whereas Olmesartan medoxomil was measured at 255nm. The coefficients of correlation were found to be 0.9997 and 0.9995 for Azelnidipine and OLME, respectively, for the RS-ERS, RS-CM AND RS-SS method and for AFM it was found to be 0.999 and 0.9995 for Azelnidipine and Olmesartan medoxomil respectively. Precision studies indicated % RSD values of less than 2% for both intra-day and inter-day measurements. The % recovery was found to be within the accepted criteria, i.e., 98-102%. The assay results met the acceptable pharmacopeial limits of 90-110%. These methods were further evaluated for their greenness using two assessment tools, namely Agree and complex Gapi.