The Influence of Arginine and Counter-Ions: Antibody Stability during Freeze-Drying

Effects of buffers on spray-freeze-dried/lyophilized high concentration protein formulations

Solid-state protein formulations are known to exhibit enhanced storage stability compared to their liquid dosage form counterparts. pH is one of the factors affecting the stability of protein formulations. The pH of protein formulations in the solution could be influenced by the buffer used, directly impacting their solid-state stability. During lyophilization, buffer components may interact with other formulation components present in the protein formulations, causing a pH shift. This study aimed to investigate the effects of phosphate buffer and amino acid buffers (such as histidine and/or arginine) on the physical properties and accelerated storage stability of spray freeze-dried or lyophilized protein formulations. A model protein, bovine serum albumin (BSA), was used to prepare high-concentration protein formulations. The formulations consisted of BSA, trehalose, and mannitol in an 80:15:5 ratio (w/w), respectively. Various buffers were utilized in the preparation of protein formulations, and the resultant solid formulations underwent screening via accelerated stability study using size exclusion chromatography (SEC). The combination of phosphate and arginine buffers resulted in increased monomer loss in the accelerated storage stability study. Additional characterizations, including solid-state Fourier transform infrared spectroscopy (ssFTIR) and powder X-ray diffraction (PXRD), were conducted. While these analyses did not definitively elucidate the mechanism behind the observed instability, their outcomes provide valuable insights for further investigation, highlighting the need for future research in this area.

"The More, the Better?": The Impact of Sugar-to-Protein Molar Ratio in Freeze-Dried Monoclonal Antibody Formulations on Protein Stability

Lyophilization is widely used to ensure the stability of protein drugs by minimizing chemical and physical degradation in the dry solid state. To this end, proteins are typically formulated with sugars that form an amorphous immobilizing matrix and stabilize hydrogen bonds replacing water molecules. The optimal amount of sugar required and protein stability at low excipient-to-protein molar ratios are not well understood. We investigated this by focusing on the physical stability of formulations, reflecting highly concentrated monoclonal antibody (mAb) lyophilizates at low sucrose to mAb ratios between 25:1 and 360:1. Additionally, the impact of different excipient types, buffer concentrations, and polysorbates was studied. The mAb stability was evaluated over up to three months at 25 and 40 °C. We investigated the "the more, the better" approach regarding excipient usage in protein formulation and the existence of a potential stabilizing threshold. Our findings show efficient monomeric content preservation even at low molar ratios, which could be explained based on the water replacement theory. We identified an exponential correlation between the sucrose to protein molar ratio and aggregate formation and found that there is no molar ratio threshold to achieve minimum stabilization. Sucrose demonstrated the best stabilization effect. Both mannitol, used as a cryoprotectant at low concentrations, and arginine reduced aggregation compared to the pure mAb formulation. The higher ionic strength of 5 mM histidine buffer enhanced protein stability compared to that of 0.1 mM histidine buffer, which was more pronounced at lower molar ratios. The addition of polysorbate 20 contributed an additional interfacial stabilizing effect, complementing the cryoprotective and lyoprotective properties of sucrose. Overall, a model could be developed to optimize the quantity of sugar required for protein stabilization and facilitate a more rational design of protein lyophilizates. The molar ratio of sugar to protein for high-concentration mAb products is limited by the acceptable tonicity, but we showed that sufficient stabilization can be achieved even at low molar ratios.

From cell factories to patients: Stability challenges in biopharmaceuticals manufacturing and administration with mitigation strategies

Active ingredients of biopharmaceuticals consist of a wide array of biomolecular structures, including those of enzymes, monoclonal antibodies, nucleic acids, and recombinant proteins. Recently, these molecules have dominated the pharmaceutical industry owing to their safety and efficacy. However, their manufacturing is hindered by high cost, inadequate batch-to-batch equivalence, inherent instability, and other quality issues. This article is an up-to-date review of the challenges encountered during different stages of biopharmaceutical production and mitigation of problems arising during their development, formulation, manufacturing, and administration. It is a broad overview discussion of stability issues encountered during product life cycle i.e., upstream processing (aggregation, solubility, host cell proteins, color change), downstream bioprocessing (aggregation, fragmentation), formulation, manufacturing, and delivery to patients.

Effects of arginine in therapeutic protein formulations: a decade review and perspectives

Arginine (Arg) is a natural amino acid with an acceptable safety profile and a unique chemical structure. Arg and its salts are highly effective in enhancing protein refolding and solubilization, suppressing protein-protein interaction and aggregation and reducing viscosity of high concentration protein formulations. Arg and its salts have been used in research and 20 approved protein injectables. This review summarizes the effects of Arg as an excipient in therapeutic protein formulations with the focus on its physicochemical properties, safety, applications in approved protein products, beneficial and detrimental effects in liquid and lyophilized protein formulations when combined with different counterions and mechanism on protein stabilization and destabilization. The decade literature review indicates that the benefits of Arg overweigh its risks when it is used appropriately. It is recommended to add Arg along with glutamate as a counterion to high concentration protein formulations on top of sugars or polyols to counterbalance the negative effects of Arg hydrochloride. The use of Arg as a viscosity reducer and protein stabilizer in high concentration formulations will be the inevitable future trend of the biopharmaceutical industry for subcutaneous administration.

Lot-to-Lot Variance in Immunoassays-Causes, Consequences, and Solutions

Immunoassays, which have gained popularity in clinical practice and modern biomedical research, play an increasingly important role in quantifying various analytes in biological samples. Despite their high sensitivity and specificity, as well as their ability to analyze multiple samples in a single run, immunoassays are plagued by the problem of lot-to-lot variance (LTLV). LTLV negatively affects assay accuracy, precision, and specificity, leading to considerable uncertainty in reported results. Therefore, maintaining consistency in technical performance over time presents a challenge in reproducing immunoassays. In this article, we share our two-decade-long experience and delve into the reasons for and locations of LTLV, as well as explore methods to mitigate its effects. Our investigation identifies potential contributing factors, including quality fluctuation in critical raw materials and deviations in manufacturing processes. These findings offer valuable insights to developers and researchers working with immunoassays, emphasizing the importance of considering lot-to-lot variance in assay development and application.

Role of Arginine Salts in Preventing Freezing-induced Increase in Subvisible Particles in Protein Formulations

While arginine hydrochloride (ArgHCl) has emerged as a potential stabilizer of protein drugs in liquid formulations the purpose of this manuscript was to evaluate its stabilization potential in frozen solutions. The phase behavior of frozen AgHCl solutions was investigated by differential scanning calorimetry and low temperature powder X-ray diffractometry. The aggregation of β-galactosidase was evaluated following freeze-thaw cycling in ArgHCl solutions with and without mannitol. ArgHCl (5% w/v) was retained amorphous in frozen aqueous solutions and effectively inhibited protein aggregation even after 5 freeze-thaw cycles. Annealing frozen arginine solution (5% w/v) containing mannitol (10% w/v) induced mannitol crystallization which in turn facilitated crystallization of ArgHCl. The stabilizing effect of ArgHCl was completely lost in the presence of mannitol. Use of alternate arginine salts (aspartate, glutamate, and acetate) allowed selective crystallization of mannitol while the arginine was retained amorphous and stabilized the protein.