Date of Award

Spring 1-1-2014

Document Type


Degree Name

Doctor of Philosophy (PhD)

First Advisor

Theodore W. Randolph

Second Advisor

John F. Carpenter

Third Advisor

Joel L. Kaar

Fourth Advisor

Daniel K. Schwartz

Fifth Advisor

Deborah S. Wuttke


Pre-filled syringes are commonly used storage and delivery devices for protein therapeutics because of their convenience and ease of use. However, in a pre-filled syringe, a protein molecule encounters several interfaces which may negatively impact its stability. In addition, protein formulations in pre-filled syringes may also be subject to agitation stresses during transportation. Exposure to interfaces and to agitation has been shown to promote aggregation and particle formation in protein formulations, and these stresses are hypothesized to work synergistically to cause more aggregation and particle generation than either stress alone.

In this work, we investigated the synergistic effects of interfaces and agitation on protein formulations in pre-filled syringes, primarily using a monoclonal antibody. First, we characterized the adsorption of this antibody to the silicone oil-water interface and showed that the tertiary structure of the antibody was perturbed after adsorption. This perturbation promoted aggregation of the antibody when it was exposed to both silicone oil microdroplets and agitation. However, when the ionic strength of the formulation was increased, the antibody was not perturbed after adsorption, and less aggregation was observed after exposure to silicone oil microdroplets and agitation.

When the antibody formulation was incubated in pre-filled syringes, the highest particle concentrations were observed in formulations that were agitated in siliconized syringes with an air bubble. From these results, we proposed an interfacial mechanism, wherein capillary forces at the three-phase contact line in the syringe pulled gelled protein aggregates and silicone oil droplets from the silicone oil-water interface into the bulk, to describe how air-water interfaces, silicone oil-water interfaces, and agitation worked synergistically to generate particles in pre-filled syringes.

Furthermore, we proposed two ways to reduce particle generation in pre-filled syringes. First, silicone oil coatings which are strongly adhered to the glass syringe wall were less able to be removed from the wall and, therefore, resulted in less particles. Second, we observed that concentrations of polysorbate 20 above and below the CMC were able to inhibit gelation of the protein layer adsorbed at the silicone oil-water interface which minimized particle generation in agitated, siliconized syringes with an air bubble.