Liquid chromatography separation and identification of new oxidative degradation impurity in edoxaban tosylate hydrate drug substance by using liquid chromatography with tandem mass spectrometry.

Edoxaban is an anti-coagulant medication and a director factor Xa inhibitor. A novel reverse phase liquid chromatography-mass spectrometry compatible method developed for separation and identification of new oxidative degradation impurities in edoxaban tosylate hydrate drug substance. The separation of three oxidative degradation impurities was achieved by using YMC Triart phenyl (250 × 4.6) mm, 5 µm column with mobile phase containing gradient elution of mobile phase-A as 10 mM ammonium acetate and mobile phase-B as acetonitrile:methanol (1:1)% (v/v). The flow rate of the mobile phase is 0.7 mL/min with a column temperature of 40 °C and detection wavelength of 290 nm. Edoxaban tosylate hydrate shows significant degradation in oxidative stress conditions and forms three oxidative degradation products. The degradation products were identified and characterized by using a high-resolution mass spectrometry quadrupole-time of flight mass detector. The three oxidative degradation impurities of Edoxaban drug substance were well resolved with each other and along with Edoxaban drug substance peak. Among the three oxidative degradation impurities di-N-oxide impurity was the new oxidative degradation impurity identified for the first time and a novel reverse-phase high-performance liquid chromatography method was developed for separation of the three oxidative degradation impurities.