Structural elucidation of the impurities in Enzalutamide bulk drug and the development, validation of corresponding HPLC method.

As the first approved androgen receptor(AR) signalling inhibitor, Enzalutamide was approved by the US Food and Drug Administration as an anticancer drug used to treat castration-resistant prostate cancer in 2012. In this manuscript, six potential impurities of Enzalutamide including process impurities and degradation products were studied. The structures of six impurities obtained by synthesis were characterized and confirmed by IR, NMR and MS techniques. In addition, an efficient chromatographic method to separate and quantify these impurities was developed, which achieved on Inertsil ODS-3 column (250mm×4.6mm,5μm) in gradient mode with a mixture of acetonitrile and the ammonium acetate buffer (10mM, pH adjusted to 4.0 with glacial acetic acid). The method was validated with respect to specificity, precision, accuracy, and sensitivity and satisfactory result was achieved. The method was demonstrated to be applicable in routine quality control and stability evaluation of Enzalutamide.