Polarographic behavior and determination of finasteride

Abstract

The polarographic behavior of finasteride at the dropping mercury electrode (DME) was studied adopting direct current (DC t), alternating current (AC t) and differential-pulse polarography (DPP) modes. In Britton–Robinson buffer (BRb), finasteride exhibited cathodic waves over the pH range 6–12. At pH 10, a well-defined cathodic wave was obtained. The latter could be characterized as being irreversible, diffusion-controlled and partially affected by adsorption phenomenon. The number of electrons involved in the reduction process was accomplished and a proposal of the electrode reaction was presented. The current–concentration plots were rectilinear over the ranges 8–40 and 2–30 μg ml −1 using DC t and DPP modes, respectively. The minimum delectability was 0.2 μg ml −1 (5.4×10 −7 M), for the latter. The proposed method was successfully applied to the determination of finasteride in its commercial capsules and the results obtained were in good agreement with those given with a reference method.