Simultaneous determination of thirteen related substances in lenalidomide API by a stability-indicating RP-HPLC...

The purpose of this study was to develop and validate a high performance liquid chromatography (HPLC) method for the separation and determination of related impurities and potential genotoxic impurity in the lenalidomide API. Chromatographic separation was performed on a Zorbax SB-AQ column (250 mm × 4.6 mm, 5 μm) at a wavelength of 220 nm using pH 4.0 phosphate buffer-acetonitrile as the mobile phase in gradient elution mode. The validation results demonstrate that the method has acceptable specificity, linearity, accuracy, precision and robustness. The detection limits and quantitation limits ranged from 2 to 17 ng/mL and from 6 to 50 ng/mL, respectively. A linear relationship was observed between the peak area and concentration of lenalidomide and impurities, with a correlation coefficient value of r ≥ 0.999. The formation and chemical structures of oxidation and base degradation products of lenalidomide have also been confirmed. The newly developed HPLC method is suitable for use in quality-control laboratories for qualitative and quantitative assessment of thirteen kinds of related substances in the lenalidomide API.