Qualitative High-Throughput Analysis of Subvisible Particles in Biological Formulations Using Backgrounded Membrane Imaging.

High-throughput analysis of low-volume samples for detection of subvisible particles (SVPs) in biologic formulations remains an unmet need in the pharmaceutical industry. Some commonly used methods, such as light obscuration and microflow imaging, for SVP analysis are not high throughput and require significant amounts of sample volume, which may impede the collection of SVP data when therapeutic protein amounts are limited, typically during early stages of formulation development. We evaluated backgrounded membrane imaging (BMI) as an orthogonal method for SVP analysis and identified critical experimental parameters. Protein concentration, sample viscosity, and membrane coverage area had to be adjusted for each sample, especially those with high protein concentrations. A comparative analysis of particle counts obtained from BMI, light obscuration, and microflow imaging for five protein samples revealed that particle counts obtained with BMI were significantly higher than those acquired with the other two techniques for all particle size categories. BMI could not accurately count particles in protein-containing samples, as the image analysis software could not accurately trace the boundaries of translucent particles. Based on our results, BMI could be used as an orthogonal method for particle characterization when sample material is limited, such as during the early stages of formulation development or screening.