Chromatographic and electrophoretic assessment of Filgrastim biosimilars in pharmaceutical formulations

An orthogonal testing protocol was developed and validated to assess the quality of Filgrastim biosimilars. Results were compared to those obtained from the innovator product. Initial screening was carried out using reducing and non-reducing gel electrophoresis. RP-LC was employed for the determination of Filgrastim in the presence of its oxidative degradation products. SEC and CIEF were used under non-denaturing conditions to reveal high molecular weight and charged impurities, respectively. RP-LC assay was found accurate (99.78±0.89) and precise over a linear concentration range of 9.38-300.00μg/ml with a LOD of 8.26μg/ml (0.44mM). SEC was carried out over a molecular weight range of 5.0-150.0kDa. CIEF was optimized using neutrally coated capillaries over a wide-range pH gradient (pH 3.0-10.0). Differences between the studied products were revealed using all these techniques. Impurities above the acceptable limits were detected in both biosimilar products. CIEF revealed heterogeneity in the active ingredient that has not been investigated by the manufacturers. Correlation of the obtained results indicated the presence of not only product-related impurities, but also process-related impurities. Results confirmed the need for in-house validated orthogonal testing protocols to be developed by local regulatory authorities. This should prevent access of substandard biosimilars to price-sensitive markets.