Spray layering of human immunoglobulin G: Optimization of formulation and process parameters.

Spray layering is a technique used to apply drug or functional polymers onto carrier beads; in addition, it can be used as an alternative method for protein drying and to layer protein on a multiparticulate delivery system. In this study, the effects of formulation variables and process parameters on human immunoglobulin G (IgG) properties during spray layering were studied. Excipients including polyvinylpyrrolidone (PVP), trehalose, sucrose, L-arginine monohydrochloride were studied for their effects on improving IgG stability during spray layering. Process parameters including protein solution feed rate, inlet air temperature, inlet air flow rate, and atomization pressure of spray solution were studied using 2 full factorial design with three replicated center points. Adding PVP into the formulation significantly decreased the turbidity of the reconstitution solution and increased the IgG recovery. Adding trehalose, sucrose, or arginine further improved protein recovery after reconstitution and decreased the percentage of IgG aggregation. The Design of Experiments (DOE) results showed no significant effects from the four process factors on the process yield and IgG protein recovery in the range of parameters studied. All main factors except atomization pressure had significant effects on monomer percentage, among which air flow represented the most significant influence. In addition, the inlet air temperature had significant effects on the in vitro binding activity of IgG after spray layering. By optimizing the formulation, we were able to recover the most spray layered IgG and reduce the IgG aggregation during the process. The DOE studies gave insight into how process variables affect the spray layered products.