First Report for the Electrooxidation of Antifungal Anidulafungin: Application To Its Voltammetric Determination in Parenteral Lyophilized Formulation Using a Boron-Doped Diamond Electrode in the Presence of Anionic Surfactant

Abstract

In this paper, for the first time, the study of electrochemical oxidation and electroanalytical determination of anidulafungin (ANF), a semi-synthetic echinocandin with antifungal activity was conducted. For this purpose, a commercially available boron-doped diamond (BDD) electrode pretreated electrochemically (anodic and subsequent cathodic) was used. Employing cyclic voltammetry, the compound presented a single and irreversible oxidation step. The electrode process is controlled by a dual mechanism of diffusion and adsorption. A systematic study of various experimental conditions, such as the effect of electrode pretreatment, pH and the nature of the supporting electrolyte, surfactant, accumulation variables, and instrumental parameters on the adsorption behavior of ANF, was carried out by using square-wave voltammetry. When the stripping mode (after 90 s accumulation at +0.3 V) was applied in 0.1 mol L-1 HNO3 containing 3x10(-4) mol L-1 SDS, there was a linear dependence between the oxidation peak current at +1.29 V and the ANF concentration in the range from 0.1 to 10.0 mu g mL(-1) (8.8x10(-8)-8.8x10(-6) mol L-1). The limit of detection value was found to be 0.021 mu g mL(-1) (1.8x10(-8) mol L-1). Practical applicability of the proposed method was demonstrated in commercial parenteral dosage form.