Determination of Azathioprine and Its Related Substances by Capillary Zone Electrophoresis and Its Application to Pharmaceutical Dosage Forms Assay

Abstract

The development of a stability-indicating capillary zone electrophoresis (CZE) method for the determination of the drug azathioprine (AZA) and its related substances in bulk and dosage forms is described. Theophylline was used as an internal standard to improve quantitative results. The method was fully validated in terms of repeatability (n = 10, RSD for migration time and peak area ratio were 0.15% and 0.60%, respectively), reproducibility (n = 5, RSD of peak area ratio was 0.84%), linearity at two ranges of the azathioprine concentration, limits of detection (LOD) and quantitation (LOQ), and robustness. The method was applied for determination of the drug in bulk and a commercial tablet dosage form (recovery 98.3–101.3%) and in powder for injection (recovery 98.7–100.6%). The method was fast and reliable for the analysis of AZA and its related substances in bulk and dosage forms.