Influence of Nano-Particulate Impurities and β-glucans on the Stability of Protein-Based Formulations

Pharmaceutical grade sugars manufactured under Current Good Manufacturing Practice (cGMP) and complied with International Pharmaceutical Excipients Council (IPEC) quality standards, also contain a significant amount of nano-particulate impurities (NPIs). This review will focus on the origin of NPIs, the mechanism of their interference with Dynamic light scattering (DLS) and endotoxin tests, filtration technology to effectively reduce the NPIs, methodologies for analytical quantification of NPIs, guidance for setting the limits of threshold concentration and the overall impact of NPIs on the therapeutic activity, performance, stability of biopharmaceuticals and protein-based formulations. NPIs with an average particle size of 100 to 200 nm are present in sugars and are a combination of various chemicals such as dextrans (with the presence of β-glucans), ash, inorganic metal salts, aromatic colorants, etc. These NPIs primarily originate from raw materials and cannot be removed during the sugar refinement process. While it is commonly believed that filtering the final formulation with a 0.22 μ sterilizing grade filter removes all microbes and particles, it is important to note that NPIs cannot be filtered using this standard sterile filtration technology. Exceeding the threshold limit of NPIs can have detrimental effects on formulations containing proteins, monoclonal Antibodies (mAbs), nucleic acids, and other biopharmaceuticals. NPIs and β-glucans have a critical impact on the functionality and therapeutic activity of biomolecules and if present below the threshold limit of reaction, stability and shelf-life of biologics formulation will be greatly improved and the risk of immunogenic reactions must be significantly decreased.