Effects of Siliconization Techniques, Headspace, Mechanical and Thermal Stress on Particle Generation in an Antibody Formulation

OBJECTIVE: Pre-filled syringes (PFSs) have become a preferred delivery system for biotherapeutics due to their convenience, accuracy, and cost-effectiveness. Silicone oil (SO) is commonly used as a lubricant in PFSs; however, its leaching can trigger immunogenicity and raise clinical and regulatory concerns. This study evaluates the impact of syringe design and handling parameters on particle formation and aggregation of a model therapeutic antibody in SO-lubricated PFSs. METHODS: The study systematically evaluated multiple factors influencing protein stability in prefilled syringes, including siliconization technique (standard sprayed-on [Stdr] vs. cross-linked [Alba®]), headspace volume (low vs. high), and applied stress conditions (slow freeze-thaw cycles and end-over-end agitation). The antibody formulation stability was assessed to determine the combined effects of these parameters on subvisible particle generation and aggregation. Comprehensive analytical characterization was performed using light obscuration (LO), micro flow imaging, size-exclusion chromatography (SEC), and analytical ultracentrifugation (AUC). RESULT: Syringes with standard sprayed-on siliconization and larger headspace volumes exhibited substantially higher subvisible particle concentrations and aggregate formation, especially under slow freeze-thaw and high-temperature end-over-end stress conditions. In contrast, syringes with cross-linked siliconization (Alba®) showed markedly reduced silicone oil particle shedding and improved protein stability across all tested stress environments. Collectively, these findings highlight that the siliconization method, headspace volume, and stress conditions act synergistically to influence aggregate formation and silicone oil particle release following fill-finish operations. CONCLUSION: Optimizing syringe design and handling parameters can significantly reduce silicone oil induced particle formation and protein aggregation, thereby improving formulation stability.