A recent USP "Stimuli to the Revision Process" article highlights the need for orthogonal methods like Flow Imaging Microscopy (FIM) to distinguish silicone oil droplets (SiOPs) from protein aggregates, as traditional light obscuration often fails to detect these low-contrast particles. Using FlowCam technology, this study demonstrates how high-resolution imaging and quantitative morphological data allow for the precise classification required to meet evolving regulatory standards.

By leveraging FIM, manufacturers can differentiate round SiOPs from irregular proteinaceous aggregates, even at the submicron level, where detailed surface textures reveal particle origins. This automated, high-throughput approach provides the comprehensive characterization necessary to ensure the safety and efficacy of modern biopharmaceuticals.