Electrochemical Redox Behavior of Omeprazole Using a Glassy Carbon Electrode

Abstract

The electrochemical redox behavior of omeprazole (OMZ), a gastric acid pump inhibitor, was investigated at a glassy carbon electrode using cyclic, differential pulse and square-wave voltammetry over a wide pH range. The pH-dependent oxidation occurs in two irreversible consecutive charge transfer reactions. Adsorption of the non-electroactive product was also observed. The first oxidation involves removal of one electron, followed by deprotonation and leads to the formation of a hydroxylated species. The second oxidation process is related to the hydroxyl and amino groups in the benzimidazole moiety. The reduction is irreversible, also pH-dependent, and occurs in a single step at the sulfoxide group in a diffusion-controlled mechanism. The diffusion coefficient of omeprazole was calculated to be D(OMZ) = 2.31 x 10(-6) cm(2) s(-1).