Determination of fesoterodine in a pharmaceutical preparation by a stability-indicating capillary zone electrophoresis method.

A simple, stability-indicating capillary zone electrophoresis (CZE) method was developed and validated for the analysis of fesoterodine (FESO) in tablets. Optimal conditions for the separation of FESO and its degradation products were investigated. The method used 10 mM sodium phosphate buffer at pH 6.5 as the background electrolyte with an applied voltage of 30 kV (positive polarity).The capillary length was 80.5 cm (72 cm to the detector), and the detection wavelength was 208 nm. The method was validated in accordance with the International Conference on Harmonization requirements, which involved specificity, linearity, precision, accuracy, robustness, LOD, and LOQ. The stability-indicating capability of the method was established by stress degradation studies combined with peak purity assessment using photodiode array detection. The method was linear over the concentration range of 2-100 microg/mL (r2 = 0.9998) of FESO. Intraday and interday precision and accuracy evaluated by RSD, respectively, were all lower than 2%. The LOD and LOQ were 0.57 and 1.90 microg/mL, respectively. The method proved to be robust by a fractional factorial design evaluation. The proposed CZE method was successfully applied for the quantitative analysis of FESO in extended-release tablets to support its QC.