Establishing Tablet Dissolution Curve Through Determination of Underivatized Alendronate Sodium by Capillary Electrophoresis-UV Detector

Background: Alendronate sodium is a common clinical osteoporosis drug for postmenopausal women; its determination is very important. However, there is no absorption of chromophores or fluorophores in the molecule, therefore, their direct determination is a challenge. Thus, establishing a common and direct method is very inspiring. Methods: According to the direct determination of alendronate sodium through the formation of a complex between alendronate sodium and divalent copper ion by capillary electrophoresis with ultraviolet detection, the dissolution profile of alendronate sodium tablet was established. The dissolution curves obtained from high-performance liquid chromatography method involving derivatization with 9- fluorenyl methylchloroformate and capillary electrophoresis with ultraviolet detector were found to be highly similar. Underivatized alendronate sodium can be determined by the capillary electrophoresis method. Results: Optimum conditions were as follows: background electrolyte including 25 mM CuSO4 at pH 4.59, 5 s injection time, 18 kV applied voltage, and 240 nm detected wavelength. Method validation indicated good linearity (r2>0.9993), precision of migration time with a relative standard deviation <1.5 % for intra-day and <3.6 % for inter-day, precision of peak areas <2.3 % for intra-day and <5.0 % for inter-day, limits of detection (0.01 μg/mL), limit of quantification (0.04 μg/mL) and recovery (90.6 %- 109.0 %). Conclusion: The proposed capillary electrophoresis method has been proved to be simpler, faster and more convenient to test dissolution profile of alendronate sodium tablet than that of high performance liquid chromatography.