Two simple spectrophotometric methods have been developed for simultaneous estimation of olmesartan medoxomil and chlorthalidone from tablet dosage form. 0.1N NaOH was used as solvent. For method A, Area under curve method, area under curve in the range of 223.7- 243.7 nm (for olmesartan medoxomil) and 213.8 - 233.8 nm (for chlorthalidone) were selected for the analysis. For method B, for the estimation of drugs by simultaneous equation method (SEM) using 233.7 and 223.8 ie. λmax values of OLM and CLT respectively. The linearity lies between 5-25 μg/mL for olmesartan medoxomil and 2- 12 μg/mL for chlorthalidone for the simultaneous equation and area under the curve method. Second method is simultaneous equation method, involves the measurement of absorbance at two wavelengths 233.7 nm (λ max of olmesartan medoxomil) and 223.8 nm (λmax of chlorthalidone). The accuracy and precision of the methods were determined and validated statically. All the methods showed good reproducibility and recovery with % RSD less than 1. The proposed methods were found to be rapid, specific, precise, accurate and can be successfully applied for the routine analysis of olmesartan medoxomil and chlorthalidone in bulk and combined tablet dosage form.
Keywords: Olmesartan Medoxomil; Chlorthalidone; Simultaneous Equation Method; Area Under Curve Method;