RESUMO
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 ß-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 ß-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.
RESUMO
The therapeutic potential for messenger RNA (mRNA) in infectious diseases and cancer was first realized almost three decades ago, but only in 2018 did the first lipid nanoparticle-based small interfering RNA (siRNA) therapy reach the market with the United States Food and Drug Administration (FDA) approval of patisiran (Onpattro™) for hereditary ATTR amyloidosis. This was largely made possible by major advances in the formulation technology for stabilized lipid-based nanoparticles (LNPs). Design of the cationic ionizable lipids, which are a key component of the LNP formulations, with an acid dissociation constant (pKa) close to the early endosomal pH, would not only ensure effective encapsulation of mRNA into the stabilized lipoplexes within the LNPs, but also its subsequent endosomal release into the cytoplasm after endocytosis. Unlike other gene therapy modalities, which require nuclear delivery, the site of action for exogenous mRNA vaccines is the cytosol where they get translated into antigenic proteins and thereby elicit an immune response. LNPs also protect the mRNA against enzymatic degradation by the omnipresent ribonucleases (RNases). Cationic nano emulsion (CNE) is also explored as an alternative and relatively thermostable mRNA vaccine delivery vehicle. In this review, we have summarized the various delivery strategies explored for mRNA vaccines, including naked mRNA injection; ex vivo loading of dendritic cells; CNE; cationic peptides; cationic polymers and finally the clinically successful COVID-19 LNP vaccines (Pfizer/BioNTech and Moderna vaccines)-their components, design principles, formulation parameter optimization and stabilization challenges. Despite the clinical success of LNP-mRNA vaccine formulations, there is a specific need to enhance their storage stability above 0 °C for these lifesaving vaccines to reach the developing world.
