Advancing Sub-Visible Particle Characterization in Inhaled Biologics

Abstract

Protein-based therapeutics represent one of the fastest growing sectors in the phar maceutical industry, offering highly specific and effective treatment options for a range of diseases. However, their structural complexity makes them particularly vulnerable to instability and aggregation, especially in formulations intended for inhalation. Protein aggregation not only compromises therapeutic efficacy but also poses a significant immunogenicity risk. Therefore, quantifying and characterizing sub-visible particles, including protein aggregates, is essential to understanding these risks and improving the overall safety and effectiveness of biologic drug products. While pulmonary drug delivery offers a non-invasive and direct route for administer ing the active pharmaceutical ingredient (API), the powders must meet specific size and property requirements. Excipients are therefore used to enhance these charac teristics and optimize the performance of the API. Conventional methods, such as Light Obscuration, are commonly used to quantify sub-visible particles, but often face challenges in detecting small and translucent particles. This thesis explores how continuous flow microscopy, specifically micro-flow imaging (MFI), can be used to differentiate and characterize sub-visible particles. By ana lyzing morphological and light intensity data of particles detected by the MFI, this study aims to identify sub-populations within drug products and their accompany ing excipients. Understanding the composition and distribution of these particles and how they contribute to the overall particulate environment in the formulations is in focus. The results reveal that different formulations exhibit particles with distinct charac teristics. Intensity distributions have been established, resulting in unique profiles that could potentially be used to identify the presence of specific formulations in un known samples. A deeper understanding of the interactions and complexities among various substances in the formulations might be required to enhance the accuracy of the identification test.