Electrochemical studies of olmesartan medoxomil and its detection in pharmaceutical dosage forms and biological fluids by cathodic adsorptive stripping voltammetric method

The electrochemical properties of olmesartan (OLME) were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) at hanging mercury drop electrode (HMDE). All studies were based on the irreversible and adsorption-controlled electrochemical reduction signal of OLME at about -1.2 and -1.5 V vs. Ag/AgCl at pH 5.0 in Britton-Robinson (BR) buffer. This adsorptive character of the molecule was used to develop a novel, fully validated, rapid, selective and simple differential pulse cathodic adsorptive stripping voltammeric (DPCAdSV) method for the direct determination of OLME in pharmaceutical dosage form and human urine without time-consuming steps prior to drug assay. Peak current of electrochemical reduction of OLME was found to vary linearly with the concentration in the range from 4.7 × 10-8 mol L-1 (0.0262 µg mL-1) to 8.3 × 10-6 mol L-1 (4.636 µg mL-1). In this method, limit of quantification (LOQ) was found to be 5.1 × 10-7 mol L-1 (0.284 µg mL-1). The method was applied to determine the content of OLME in commercial pharmaceutical preparation and spiked human urine. It was found to be highly accurate and precise, having a relative standard deviation of less than 10% for all applications.