Investigation of the profile and kinetics of degradation of rivaroxaban using HPLC, TLC-densitometry and LC/MS/MS: Application to pre-formulation studies

Rivaroxaban (RIVA), an amide group-containing oral anticoagulant was subjected to stress conditions commonly required for the registration of pharmaceuticals: base and acid-catalyzed hydrolysis (0.1 M, 60 °C, 3–6 h), oxidation (10% H2O2, 24 h), photodegradation (300–800 nm, 24 h) and thermal decomposition (50 °C, 6 h). Two major degradation products were separated and identified using TLC and LC/MS/MS, respectively. An orthogonal stability-indicating testing protocol (RP-HPLC and NP-TLC-densitometry) was developed and validated according to ICH guidelines. Both assays enabled the determination of RIVA in the presence of its degradation products as well as the kinetics of degradation. Determination was carried out over a concentration range of (5.00–50.00 μg/mL) and (0.40–12.00 μg/band) with an accuracy of (100.81% ± 1.03) and (100.29% ± 1.08) for HPLC and TLC-densitometry, respectively. Results indicated that RIVA was stable towards oxidation, photodegradation and thermal decomposition but extremely sensitive to hydrolysis. Two major degradation products were detected in the case of base-catalyzed hydrolysis while only one degradation product was detected upon acid-catalyzed hydrolysis. This could be attributed to the presence of amide groups in RIVA structure of different stability profiles. The kinetics of hydrolysis was investigated in more detail and the reaction was found to follow the pseudo first order kinetics, as confirmed by the results of both HPLC and TLC-densitometric assays. The applicability of the assay for the determination of RIVA content and dissolution pattern of the innovator product as well as three generic formulations was demonstrated.