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

Area of Science:

• Biopharmaceutical processing
• Protein stabilization technologies

Background:

• Polyclonal immunoglobulin G (IgG) is a critical biopharmaceutical.
• Maintaining IgG stability during freeze-drying (lyophilization) is essential for therapeutic efficacy.
• Understanding the impact of processing parameters and formulation is key to optimizing lyophilization cycles.

Purpose of the Study:

• To investigate how freeze-drying parameters and formulation affect polyclonal IgG stability.
• To determine the influence of primary and secondary drying conditions on IgG characteristics.
• To assess the role of specific formulation components, like sodium phosphate buffer, in IgG stability.

Main Methods:

• Freeze-drying of polyclonal IgG samples under varying primary drying pressures and secondary drying heating rates.
• Analysis of rehydrated lyophilizates for IgG in vitro binding activity, monomer recovery, particle size, and polydispersity.
• Comparative analysis of formulations with and without sodium phosphate buffer.

Main Results:

• Lower primary drying pressures led to increased average particle size and polydispersity in rehydrated IgG.
• These increases in particle size and polydispersity were mitigated by removing sodium phosphate buffer from the formulation.
• No significant changes in IgG binding activity or monomer recovery were observed.
• Altering secondary drying heating rates did not measurably affect protein stability.

Conclusions:

• Primary drying pressure is a critical parameter influencing IgG aggregation during freeze-drying, particularly in the presence of sodium phosphate buffer.
• Formulation composition, specifically the presence of sodium phosphate buffer, plays a significant role in mitigating IgG structural changes during lyophilization.
• Secondary drying conditions appear to have a minimal impact on the stability of polyclonal IgG under the tested parameters.