The effect of freeze-drying parameters and formulation composition on IgG stability during drying.

The objective of this study was to explore the effects of freeze-drying parameters and formulation composition on polyclonal IgG stability during processing. Samples were freeze-dried with different primary drying pressures and secondary drying heating rates. After drying, changes in IgG in vitro binding activity, monomer recovery, average particle size, and polydispersity were studied from the rehydrated lyophilizates. Significant trends were not observed in binding activities or monomer recoveries, but increases in particle size and polydispersity were observed when using lower primary drying pressure. This effect could no longer be observed when sodium phosphate buffer was removed from the formulation. Altering the secondary drying heating rates did not result in any measurable changes in protein stability.