Apparent degradation forms of rhG-CSF under forced conditions: Insights for better quality-control of bioproducts

Stability and quality control of therapeutic protein formulations is a substantial part of drug development process. The objective of this study is to obtain information about stability of a recombinant human granulocyte colony stimulating factor (rhG-CSF) against various stress factors. This will play a crucial role in the finished product formulation development. In this study, rhG-CSF was exposed to various chemical and physical stress conditions at different levels in order to identify degradation pathways and the nature of impurities generated. Experiments were performed by a combination of orthogonal analytical techniques (reversed phase chromatography (RP-HPLC), size exclusion chromatography (SEC-HPLC), polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF)) to set and characterize the different degraded samples. The SEC-HPLC results suggest that the major degradation factors generating aggregated forms of the protein are basically thermal stress, freeze-thaw cycles and vortexing. Meanwhile, deamidated rhG-CSF was induced by basic pH as shown by IEF electrophoregram. As well, oxidized forms were generated increasingly with the time of exposure to hydrogen peroxide as outlined by RP-HPLC analysis. Based on these results, it was possible to define the storage and handling conditions of rhG-CSF finished product during its shelf life.