Validation of a stability-indicating micellar electrokinetic capillary method for the assessment of febuxostat and its correlation with the reversed-phase LC method

Abstract

A stability-indicating micellar electrokinetic capillary chromatography (MEKC) method was validated for the analysis of febuxostat in pharmaceutical formulations, using lisinopril as the internal standard (IS). A fused-silica capillary (50 μm i.d.; effective length, 40 cm) was maintained at 30 °C, and the applied voltage was 20 kV. The background electrolyte solution consisted of 15 mmol L⁻¹ sodium tetraborate buffer and 25 mmol L⁻¹ sodium dodecyl sulphate solution at pH 10. Injections were performed using a pressure mode at 50 mbar for 45 s, with detection using a photodiode array detector set at 216 nm. Specificity and stability-indicating capability were established in degradation studies, which also showed that there was no interference of the excipients. The method was linear over the concentration range of 0.10–50 μg mL⁻¹ (r² = 0.9993) and the limit of detection (LOD) and limit of quantitation (LOQ) were 0.05 μg mL⁻¹ and 0.10 μg mL⁻¹, respectively. The accuracy was 99.89% with a relative error lower than 1.04%. The proposed method was applied to the quantitative analysis of febuxostat in tablet dosage forms and in human plasma, and the results were correlated with those of a validated reversed-phase (RP-LC) method, in attempts to improve quality control of pharmaceutical products.