Simultaneous Spectroscopic Estimation of Amlodipine Besylate and Olmesartan Medoximil in Tablet Dosage Form

A simple, accurate and precise spectroscopic method was developed for simultaneous determination of Amlodipine besylate and Olmesartan medoximil in tablets using first derivative zero crossing method. Amlodipine showed zero crossing point at 237 nm while olmesartan showed zero crossing at 259 nm. The dA/dλ was measured at 259 nm for amlodipine and 237 nm for olmesartan and calibration curves were plotted as dA/dλ versus concentration, respectively. The method was found to be linear from 5 -30 μg/mL for amlodipine (r² ≥ 0.9999) at 259 nm and 5 -30 μg mL⁻¹ for olmesartan (r² ≥ 0.9998) at 237 nm. The within day and between day variations showed coefficient of variation (CV%) values less than 1.5% for both drugs. The limit of detection was 0.06 and 0.14 μg/mL for amlodipine and olmesartan, respectively. The limit of quantification was 0.18 and 0.43 μg/mL for amlodipine and olmesartan, respectively. The method was successfully applied for simultaneous determination both drug in tablet dosage form.