Development and Validation of Dual Wavelength UV Spectrophotometric Method for simultaneous estimation of Cilnidipine and Olmesartan Medoxomil in Tablet dosage form

Abstract

A simple and economical dual wavelength spectrophotometric method has been developed for the simultaneous estimation of Cilnidipine and Olmesartan Medoxomil in their tablet dosage form. The principle for dual wavelength method is “the absorbance difference between two points on the overlain spectra is directly proportional to the concentration of the component of interest”. From the UV absorption spectrum of Cilnidipine, three wavelengths were selected, which were 282.99, 337.85 and 352.92 nm. At 352.92 nm only Cilnidipine has reasonable absorbance, so it was selected for the estimation of it from combination drug product. At these two wavelengths absorbance for Cilnidipine was found to be same i.e. absorbance difference was zero for any concentration, while for Olmesartan Medoxomil concomitantly increase in absorbance difference with increase in its concentration. So, 282.99 and 337.85 nm wavelengths were selected for the estimation of Olmesartan Medoxomil from its combination drug product. The method involved solving of an equation based on measurement of absorbances at two wavelengths 282.99 and 337.85 nm. Regression analysis of Beer’s plots showed good correlation in concentration range of 10-60 μg/ml for Cilnidipine and 20-120 μg/ml for Olmesartan Medoxomil. The suitability of this method was for quantitative determination of Cilnidipine and Olmesartan Medoxomil was proved by validation and recovery study. The proposed method was found to be simple, rapid, economical, accurate and reproducible for the routine analysis of both drugs in tablet dosage forms.