Simultaneous Estimation of Amlodipine Besylate and Telmisartan by UV-Spectrophotometry

Three simple, accurate, economic, precise and reproducible spectrophotometric methods are developed for simultaneous estimation of telmisartan and amlodipine besylate in combined tablet dosage form. First developed method involves formation and solving of simultaneous equation at 297.0 nm for estimation of telmisartan and amlodipine besylate is estimated from the calibration curve at 362.0 nm. Second developed method makes use absorbance ratio method using 324.0 nm as isobestic point. Third developed method is based on first derivative spectroscopy using 236.0 nm as zero crossing point. Methanol and 0.1 N sodium hydroxide in the ratio 5:5 was used as solvent for all three methods. All the developed methods obey Beer's law in the concentration ranges employed for the respective methods. The results of analysis were validated statistically and by recovery studies.