Redox Pathways of Aliskiren Based on Experimental and Computational Approach and Its Voltammetric Determination

Electrochemical behavior of aliskiren (ALS) was studied via experimental electrochemical methods and theoretical calculations performed at B3LYP/6-31+G (d)//AM1. Cyclic voltammetry studies were carried out based on the adsorption-controlled reversible reduction at ca. -1.5 V on hanging mercury drop electrode (HMDE) and irreversible electrochemical oxidation of ALS at ca. 1.0 V on glassy carbon electrode (GCE), vs. Ag/AgCl, KCl (3.0 mol L-1), in Britton-Robinson buffer at pH 10 and 8, respectively. According to computational and experimental findings, ALS is expected to be oxidized irreversibly at benzylic position and reduced reversibly at amide carbonyl groups. Voltammetric methods with and without adsorptive stripping mode were developed and validated for quantification of ALS in different samples. Limits of detection and of quantification for ALS were 6.3 x 10(-8) and 2.1 x 10(-7) mol L-1 for differential pulse voltammetry on HMDE and 1.2 x 10(-8) and 3.9 x 10(-8) mol L-1 for square-wave cathodic adsorptive stripping voltammetry. The methods were successfully applied to assay the drug in tablets and human serum with good recoveries, between 91.7 and 102.3%, having relative standard deviation less than 10%.