Simultaneous Estimation of Amlodipine Besylate and Olmesartan Medoxomil in Combined Tablet Dosage Form Using UV-Spectroscopy and Reverse Phase High-Performance Liquid Chromatography Method

Simple, accurate and precise ultraviolet spectrophotometric and reversed-phase high-performance liquid chromatographic (RP-HPLC) methods for simultaneous estimation of amlodipine besylate (AMLO) and olmesartan medoxomil (OLME) in combined tablet dosage form have been developed and validated. Beer’s law was obeyed in the concentration range of 5-70 and 5-60 μg/mL in methanol at 238 nm and 257 nm for AMLO and OLME, respectively for simultaneous equation method. The RP-HPLC method uses a Shimadzu LC 10 ATVP system with Luna C18 column and acetonitrile: phosphate buffer (pH 4.0) (42:58 v/v) as the mobile phase. The detection was carried out using a diode array detector set at 238 nm. Linearity of chromatographic method was found in the concentration range of 2-40 and 8– 160 μg/mL for AMLO and OLME respectively. The recoveries were in the range of 99.79 ± 0.161% and 100.12 ± 0.446% for AMLO, 99.85 ± 0.275% and 99.98 ± 0.404% for OLME in simultaneous equation method and HPLC methods respectively. Both methods may be used for routine analysis of the drugs in a pharmaceutical formulation. Results of analysis were validated statistically. _____________________________________________________________________________________________________________