Anodic voltammetric behavior and determination of antihistaminic agent: Fexofenadine HCl

A voltammetric study of the oxidation of fexofenadine HCl (FEXO) has been carried out at the glassy carbon electrode. The electrochemical oxidation of FEXO was investigated by cyclic, linear sweep, differential pulse (DPV), and square wave (SWV) voltammetry using glassy carbon electrode. The oxidation of FEXO was irreversible and exhibited diffusion-controlled process depending on pH. The dependence of intensities of currents and potentials on pH, concentration, scan rate, nature of the buffer was investigated. Different parameters were tested to optimize the conditions for the determination of FEXO. For analytical purposes, a very well resolved diffusion-controlled voltammetric peak was obtained in Britton-Robinson buffer at pH 7.0 with 20% constant amount of methanol for DPV and SWV techniques. The linear response was obtained in supporting electrolyte in the ranges of 1.0 × 10^-6-2.0 × 10^-4 M with a detection limit of 6.6 × 10^-9 M and 5.76 × 10^-8 M and in serum samples in the ranges of 2.0 × 10^-6-1.0 × 10^-4 M with a detection limit of 8.08 × 10^-8 M and 4.97 × 10^-8 M for differential pulse and square wave voltammetric techniques, respectively. Only square wave voltammetric technique can be applied to the urine samples, and the linearity was obtained in the ranges of 2.0 × 10^-6-1.0 × 10 ^-4 M with a detection limit of 2.00 × 10^-7 M. Based on this study, simple, rapid, selective and sensitive two voltammetric methods were developed for the determination of FEXO in dosage forms and biological fluids. For the precision and accuracy of the developed methods, recovery studies were used. The standard addition method was used for the recovery studies. No electroactive interferences were found in biological fluids from the endogenous substances and additives present in tablets.