Investigation of degradation in the biosimilar structure of rituximab (Zitax) after dilution and storage in the refrigerator

Abstract

Introduction: Monochlonal antibodies (mAbs) are a class of biopharmaceutical products mostly used as therapeutic agents. Rituximab (RTX), is a chimeric mAb that has many biosimilars. Zytux® is a biosimilar of the anti-CD20 monoclonal antibody, rituximab, and is approved for use in the treatment of non-Hodgkin’s lymphoma, chronic lymphocytic leukemia, rheumatoid arthritis, granulomatosis with polyangiitis, and microscopic polyangiitis. In-use stability studies play a crucial role in determining how various conditions, such as storage duration affect the quality of the drug after dilution and storage.Aim: This study aimed to evaluate the physicochemical stability of diluted Zytux® at concentrations of 1 mg/ml and 4 mg/ml following preparation and refrigerated storage for up to 42 days.Method: Several protein characterization methods, including Native-Page, dynamic light scattering, cation-exchange chromatography, and second-derivative FTIR spectroscopy, were employed to assess changes in the physicochemical properties of Zytux®.Results: The experimental data revealed a decrease in stability of diluted Zytux® after being stored in the refrigerator for one day, irrespective of the concentration.Conclusion: While definitive conclusions regarding the stability of diluted Zytux® solutions require further studies and alternative methods to validate the obtained results, this thesis suggests that it is advisable to use diluted Zytux® solution immediately after dilution. If refrigeration storage is necessary, it is recommended to utilize the solution within one day, after which it should be discarded. These recommendations, based on the findings of this study, provide initial guidance for the handling and usage of diluted Zytux® solutions. Further research is warranted to explore and confirm the stability aspects of these solutions