Effect of Molecular Weight and Ratio of Poly Ethylene Glycols' Derivatives in Combination with Trehalose on Stability of Freeze- Dried IgG.

The influence of poly ethylene glycol (PEG) at different molecular weights (MWs) and ratios was studied on the stability of freeze-dried immune globulin G (IgG). PEGs (600-4000 Dalton) at concentrations of 0.5 and 5% W/V were applied in the presence of 40 and 60% W/W of trehalose to prepare freeze-dried IgG formulations. Size-exclusion chromatography, infra-red spectroscopy, differential scanning calorimeter, and gel electrophoresis were performed to characterize lyophilized samples. Pure IgG demonstrated the highest aggregation of 5.77 +/- 0.10% after process and 12.66 +/- 0.50% as well as 44.69 +/- 0.50% upon 1 and 2months of storage at 45 degrees C, respectively. 5% W/V of PEGs 4000 in combination with 40% W/W trehalose, significantly suppressed aggregation, 0.05 +/- 0.01%, with minimum aggregation rate constant of 0.32 (1/month). The integrity of IgG molecules and secondary conformation were properly preserved in all formulations comparing native IgG. It could be concluded that appropriate concentration and MW of PEGs, prominently augmented stabilizing effect of trehalose on freeze-dried antibody through inserting additional supportive mechanisms of actions.