Analysis of an antibody pharmaceutical, tocilizumab, by capillary electrophoresis using a carboxylated capillary

Antibody pharmaceuticals are becoming more and more prevalent due to their excellent effectiveness in clinical medications, and are expected to allow tailor-made medical treatment for rheumatic diseases, immunosuppression in cardiac transplantation, and cancer. Antibody-type pharmaceuticals of immunoglobulin G (IgG) commonly have N-glycosylated carbohydrate chains attached to heavy chains. The carbohydrate chains play important roles in the effectiveness of antibodies. Therefore evaluation of a glycosylated species is important in the first step of quality control of antibody pharmaceuticals. In the present work, we examined capillary electrophoresis with a newly developed, chemically modified capillary, the inner surface of which is modified with carboxyl groups, for evaluation of IgG molecular species which have carbohydrate chains; tocilizumab was used as a model. The analytical system developed in the present study is useful for determining the content of non-glycosylated peptides. In the analysis of tocilizumab, the ratio of non-glycosylated peptide was estimated to be 1.23% with a relative standard deviation of 3.05%. The method affords high reproducibility with simple operation, and analysis can be completed within 6 min.