Profiling polysorbate 80 components using comprehensive liquid chromatography-tandem mass spectrometry analysis

Detailed profiling of polysorbate 80 oxidative degradation products and hydrolysates using liquid chromatography-tandem mass spectrometry analysis

RATIONALE

Polysorbate 80 (PS80) is an amphipathic, nonionic surfactant that is commonly used to stabilize proteins in biopharmaceutical formulations. PS80 undergoes oxidative and/or enzymatic degradation. However, because PS80 is a complex mixture consisting of many constituents, comprehensive evaluations of its oxidative degradation products are difficult and insufficient.

METHODS

Our previously reported comprehensive liquid chromatography-tandem mass spectrometry (LC/MS/MS)-based method for PS80 effectively provides an overall profile of PS80 components under simple LC conditions. In this study, we attempted to shorten the analysis time. Furthermore, PS80 was oxidatively degraded in a solution containing histidine and iron, and the oxidative degradation products were evaluated using a modified LC/MS/MS method. In addition, enzymatically hydrolyzed PS80 samples were analyzed.

RESULTS

We succeeded in shortening the analysis time from 70 to 20 min while maintaining the resolution of the PS80 components of the same selected reaction monitoring transition. Both the previously reported oxidative degradation products and the newly discovered products were successfully detected, and their composition ratios and changes over time were observed. Changes in the hydrolysates over time are shown in the analysis of the hydrolyzed PS80 samples.

CONCLUSIONS

This study clearly showed the presence of changes in PS80 oxidative and/or enzymatic degradation products, including those previously unreported. These results demonstrate that a detailed profiling of PS80 degradation products can be performed using LC/MS/MS, which is less expensive and more generally adopted than high-resolution MS.

Optimizing Excipient Properties to Prevent Aggregation in Biopharmaceutical Formulations

Excipients are included within protein biotherapeutic solution formulations to improve colloidal and conformational stability but are generally not designed for the specific purpose of preventing aggregation and improving cryoprotection in solution. In this work, we have explored the relationship between the structure and antiaggregation activity of excipients by utilizing coarse-grained molecular dynamics modeling of protein-excipient interaction. We have studied human serum albumin as a model protein, and we report the interaction of 41 excipients (polysorbates, fatty alcohol ethoxylates, fatty acid ethoxylates, phospholipids, glucosides, amino acids, and others) in terms of the reduction of solvent accessible surface area of aggregation-prone regions, proposed as a mechanism of aggregation prevention. Polyoxyethylene sorbitan had the greatest degree of interaction with aggregation-prone regions, decreasing the solvent accessible surface area of APRs by 20.7 nm2 (40.1%). Physicochemical descriptors generated by Mordred are employed to probe the structure-property relationship using partial least-squares regression. A leave-one-out cross-validated model had a root-mean-square error of prediction of 4.1 nm2 and a mean relative error of prediction of 0.077. Generally, longer molecules with a large number of alcohol-terminated PEG units tended to interact more, with qualitatively different protein interactions, wrapping around the protein. Shorter or less ethoxylated compounds tend to form hemimicellar clusters at the protein surface. We propose that an improved design would feature many short chains of 5 to 10 PEG units in many distinct branches and at least some hydrophobic content in the form of medium-length or greater aliphatic chains (i.e., six or more carbon atoms). The combination of molecular dynamics simulation and quantitative modeling is an important first step in an all-purpose protein-independent model for the computer-aided design of stabilizing excipients.

Degradation of polysorbate investigated by a high-performance liquid chromatography multi-detector system with charged aerosol and mass detection

Polysorbate 80 is widely used as a formulation component in biopharmaceutical drug products. Recent studies have shown that polysorbate 80 is readily degraded either through direct or indirect means. The degradation of polysorbate 80 causes a concern for the long-term stability of biopharmaceutical drug product, as the breakdown products of polysorbate 80 have been shown to cause adverse effects, such as formation of sub-visible and visible particles and mAb aggregation. Understanding the path and extent of degradation is of a paramount importance for the formulator during formulation development. A multi-detector HPLC system using charged aerosol and mass detection was developed and optimized for the characterization of polysorbate 80 standards. The system included a post-column make-up flow, i.e. an inverse gradient, that enabled constant eluent composition at the detectors. The inverse gradient eliminated the main source of variability for the charged aerosol detector response, thereby enabling the calculation of the mass balance between polysorbate components with different degrees of esterification. Extracted ion chromatograms of the mass detector combined with their respective retention times were used to qualitatively characterize the polysorbate samples down to the individual components. The system was applied to study the degradation of several polysorbate standards which occurred by enzymatic digestion or long-term storage. The system provided detailed information on the mechanism of degradation without the need for additional orthogonal analytical techniques.

Primary Processes of Free Radical Formation in Pharmaceutical Formulations of Therapeutic Proteins

Oxidation represents a major pathway for the chemical degradation of pharmaceutical formulations. Few specific details are available on the mechanisms that trigger oxidation reactions in these formulations, specifically with respect to the formation of free radicals. Hence, these mechanisms must be formulated based on information on impurities and stress factors resulting from manufacturing, transportation and storage. In more detail, this article focusses on autoxidation, metal-catalyzed oxidation, photo-degradation and radicals generated from cavitation as a result of mechanical stress. Emphasis is placed on probable rather than theoretically possible pathways.