Polysorbate stability: Effects of packaging materials, buffers, counterions, and pH.

Polysorbates, widely used excipients in drug formulations, present a stability challenge due to complex degradation processes. This study investigates the hydrolysis of polysorbate (PS) under temperature stress (50 °C), focusing on the impact of primary packaging materials (glass vs. plastic vials), buffers (histidine and acetic acid), counterions (chloride vs. malate), and pH (4-7). Our findings reveal that leachables from plastic vials inhibit PS degradation in both histidine and acetic acid buffers. Kinetic parameters derived from sigmoidal fitting suggest distinct degradation mechanisms for each buffer. Furthermore, the malate counterion with histidine displays inhibitory effects on PS hydrolysis. Principal component analysis was employed to identify key factors. These results highlight the critical role of excipients and packaging in PS stability, providing valuable insights for biopharmaceutical formulation development and a deeper understanding of PS degradation complexities.

Alternative buffer systems in biopharmaceutical formulations and their effect on protein stability.

The formulation of biopharmaceutical drugs is designed to eliminate chemical instabilities, increase conformational and colloidal stability of proteins, and optimize interfacial stability. Among the various excipients involved, buffer composition plays a pivotal role. However, conventional buffers like histidine and phosphate buffers may not always be the optimal choice for all monoclonal antibodies (mAbs). In this study, we investigated the effects of several alternative buffer systems on seven different mAbs, exploring various combinations of ionic strengths, concentrations of the main buffer component, mAb concentrations, and stress conditions. Protein stability was assessed by analyzing soluble aggregate formation through size exclusion chromatography. At low protein concentrations, protein instability after temperature stress was exclusively observed in the bis-TRIS/ glucuronate buffer. Conversely, freeze-thaw stress led to a significant increase in aggregate formation in tested formulations, highlighting the efficacy of several alternative buffers, particularly arginine/ citrate, in preserving protein stability. Under temperature stress, the introduction of arginine to histidine buffer systems provided additional stabilization, while the addition of lysine resulted in protein destabilization. Similarly, the incorporation of arginine into histi-dine/HCl buffer further enhanced protein stability during freeze--thaw cycles. At high protein concentrations, the histidine/citrate buffer emerged as one of the most optimal choices for addressing temperature and light-induced stress. The efficacy of histidine buffers in combating light stress might be attributed to the light-absorbing properties of histidine molecules. Our findings demonstrate that the development of biopharmaceutical formulations should not be confined to conventional buffer systems, as numerous alternative options exhibit comparable or even superior performance.

The search for novel proline analogs for viscosity reduction and stabilization of highly concentrated monoclonal antibody solutions.

Administration of monoclonal antibodies (mAbs) is currently focused on subcutaneous injection associated with increased patient adherence and reduced treatment cost, leading to sustainable healthcare. The main bottleneck is low volume that can be injected, requiring highly concentrated mAb solutions. The latter results in increased solution viscosity with pronounced mAb aggregation propensity because of intensive protein-protein interactions. Small molecule excipients have been proposed to restrict the protein-protein interactions, contributing to reduced viscosity. The aim of the study was to discover novel compounds that reduce the viscosity of highly concentrated mAb solution. First, the chemical space of proline analogs was explored and 35 compounds were determined. Viscosity measurements revealed that 18 proline analogs reduced the mAb solution viscosity similar to or more than proline. The compounds forming both electrostatic and hydrophobic interactions with mAb reduced the viscosity of the formulation more efficiently without detrimentally effecting mAb physical stability. A correlation between the level of interaction and viscosity-reducing effect was confirmed with molecular dynamic simulations. Structure rigidity of the compounds and aromaticity contributed to their viscosity-reducing effect, dependent on molecule size. The study results highlight the novel proline analogs as an effective approach in viscosity reduction in development of biopharmaceuticals for subcutaneous administration.

Discovery of compounds with viscosity-reducing effects on biopharmaceutical formulations with monoclonal antibodies.

For the development of concentrated monoclonal antibody formulations for subcutaneous administration, the main challenge is the high viscosity of the solutions. To compensate for this, viscosity reducing agents are commonly used as excipients. Here, we applied two computational chemistry approaches to discover new viscosity-reducing agents: fingerprint similarity searching, and physicochemical property filtering. In total, 94 compounds were selected and experimentally evaluated on two model monoclonal antibodies, which led to the discovery of 44 new viscosity-reducing agents. Analysis of the results showed that using a simple filter that selects only compounds with three or more charge groups is a good 'rule of thumb' for selecting potential viscosity-reducing agents for two model monoclonal antibody formulations.