Reduced Subvisible Particle Formation in Lyophilized Intravenous Immunoglobulin Formulations Containing Polysorbate 20

The first goal of this study was to determine the effects of the surface fraction of protein in lyophilized formulations of intravenous immunoglobulin on protein stability during long-term storage. We attempted to modulate surface fraction by either including polysorbate 20 (PS20) in the formulation or performing pre-drying annealing during lyophilization, but neither approach reduced surface fraction. Our second goal was to study the effects of formulation and processing conditions on protein aggregation and subvisible particle formation. If formulations were reconstituted immediately after lyophilization, protein aggregation detected by size exclusion chromatography was insignificant. However, with the higher resolution of damage afforded by subvisible particle analysis, it was found that high levels of particles were produced in the formulation containing trehalose and that the presence of PS20 greatly reduced particle concentrations. Size exclusion chromatography analysis showed that in formulations without trehalose during storage for 16 weeks at 50°C, there was loss of monomer and a concomitant increase in aggregates. In formulations containing trehalose there were no significant increases in aggregation or subvisible particle levels. Finally, we observed that inclusion of PS20 in the water used to reconstitute lyophilized formulations without PS20 reduced the formation of protein particles; documenting that protection by the surfactant occurred during reconstitution as well as during lyophilization.