Pulse polarographic (constant and increasing) determinations of doxazosin in pharmaceutical tablets

The optimum conditions using DC polarography and the determination of doxazosin employing SIAP and SCAP polarographic techniques are described in this study. All the experiments were conducted in the supporting electrolyte consisting of 20% ethanol (v/v), 0.2 M KCl and 0.2 M acetate buffer at various pH values in order to examine the optimum conditions, and pH 3.5 for the determination of doxazosin. Well-defined curves were obtained in the pH range of 1.5-7.5. The system was diffusional and irreversible at pH 3.5. The calibration studies were performed by using SIAP and SCAP polarography and satisfactory results were observed for all techniques. Since the sensitivity of SIAP and SCAP techniques were higher than the others, the determination of doxazosin was performed in filtered and unfiltered tablet solutions containing 4 mg active material. In the analysis of a tablet, the relative standard deviations (Srel %) of the techniques are in the filtered solutions +/- 0.9 (SIAP), +/- 0.8 (SCAP) and in the unfiltered solutions +/- 0.7 (SIAP), +/- 0.8 (SCAP) and no interference was observed during the analysis. The determination methods proposed in this study appear to be accurate, rapid and practicable. Therefore, these techniques may be suitable for the content uniformity tests.