A multi-step machine learning approach for accelerating QbD-based process development of protein spray drying

This study proposes a new material-efficient multi-step machine learning (ML) approach for the development of a design space (DS) for spray drying proteins. Typically, a DS is developed by performing a design of experiments (DoE) with the spray dryer and the protein of interest, followed by deriving the DoE models via multi-variate regression. This approach was followed as a benchmark to the ML approach. The more complex the process and required accuracy of the final model is, the more experiments are necessary. However, most biologics are expensive and thus experiments should be kept to a minimum. Therefore, the suitability of using a surrogate material and ML for the development of a DS was investigated. To this end, a DoE was performed with the surrogate and the data used for training the ML approach. The ML and DoE model predictions were compared to measurements of three protein-based validation runs. The suitability of using lactose as surrogate was investigated and advantages of the proposed approach were demonstrated. Limitations were identified at protein concentrations >35mg/ml and particle sizes of x₅₀>6µm. Within the investigated DS protein secondary structure was preserved, and most process settings, resulted in yields >75% and residual moisture <10wt.%.

Accelerated Production of Biopharmaceuticals via Microwave-Assisted Freeze-Drying (MFD)

Recently, attention has been drawn to microwave-assisted freeze-drying (MFD), as it drastically reduces the typically long drying times of biopharmaceuticals in conventional freeze-drying (CFD). Nevertheless, previously described prototype machines lack important attributes such as in-chamber freezing and stoppering, not allowing for the performance of representative vial freeze-drying processes. In this study, we present a new technical MFD setup, designed with GMP processes in mind. It is based on a standard lyophilizer equipped with flat semiconductor microwave modules. The idea was to enable the retrofitting of standard freeze-dryers with a microwave option, which would reduce the hurdles of implementation. We aimed to collect process data with respect to the speed, settings, and controllability of the MFD processes. Moreover, we studied the performance of six monoclonal antibody (mAb) formulations in terms of quality after drying and stability after storage for 6 months. We found drying processes to be drastically shortened and well controllable and observed no signs of plasma discharge. The characterization of the lyophilizates revealed an elegant cake appearance and remarkably good stability in the mAb after MFD. Furthermore, overall storage stability was good, even when residual moisture was increased due to high concentrations of glass-forming excipients. A direct comparison of stability data following MFD and CFD demonstrated similar stability profiles. We conclude that the new machine design is highly advantageous, enabling the fast-drying of excipient-dominated, low-concentrated mAb formulations in compliance with modern manufacturing technology.

In-vial printing and drying of biologics as a personalizable approach

This study addressed the need for a flexible (personalizable) production of biologics, allowing their stabilization in the solid state and processing of small batch volumes. Therefore, inkjet printing into vials followed by a gentle vacuum drying step at ambient temperature was investigated by screening different formulations with a 2²-full factorial design of experiments regarding printability. Human Serum Albumin (HSA) was used as a model protein in a wide range of concentrations (5 to 50 mg/ml), with (10 w/v%) and without the surfactant polysorbate 80 (PS80). PS80 was identified to positively affect the formulations by increasing the Ohnesorge number and stabilizing the printing process. The dispensed volumes with a target dose of 0.5 mg HSA were dried and analyzed concerning their residual moisture (RM) and protein aggregation. All investigated formulations showed an RM < 10 wt% and no significant induced protein aggregation as confirmed by Size Exclusion Chromatography (<2.5%) and Dynamic Light Scattering (Aggregation Index ≤ 2.5). Additionally, long-term printability and the available final dose after reconstitution were investigated for two optimized formulations. A promising formulation providing ∼93% of the targeted dose and a reconstitution time of 30 s was identified.

Application of ultraviolet, visible, and infrared light imaging in protein-based biopharmaceutical formulation characterization and development studies

Imaging is increasingly more utilized as analytical technology in biopharmaceutical formulation research, with applications ranging from subvisible particle characterization to thermal stability screening and residual moisture analysis. This review offers a comprehensive overview of analytical imaging for scientists active in biopharmaceutical formulation research and development, where it presents the unique information provided by the ultraviolet (UV), visible (Vis), and infrared (IR) sections in the electromagnetic spectrum. The main body of this review consists of an outline of UV, Vis, and IR imaging techniques for several (bio)physical properties that are commonly determined during protein-based biopharmaceutical formulation characterization and development studies. The review concludes with a future perspective of applied imaging within the field of biopharmaceutical formulation research.

Freeze-drying: A relevant unit operation in the manufacture of foods, nutritional products, and pharmaceuticals

Freeze-drying, a drying unit operation frequently used in food, pharmaceutical, and biopharmaceutical industries to prolong the shelf life of labile products, is an energy-intensive, time-consuming, and expensive process. Although all three steps (freezing, primary drying, and secondary drying) of freeze-drying are important, primary drying is the longest and most critical one. As sublimation during primary drying is mainly described in terms of heat and mass transfer, the present work provides extensive theoretical and experimental analyses of these processes. First, a detailed review of the current state-of-the art of freeze-drying, focusing on the drying stage, is given, which contributes to a fundamental understanding of the drying process. Second, a detailed experimental study of the drying section of the freeze-drying process is discussed, furnishing information on the relationship between input and output process parameters during the primary drying stage and thus aiding freeze-drying process design and optimization. In this regard, the influence of primary drying input parameters (i.e., shelf temperature and chamber pressure) and vial position on output parameters such as product temperature, sublimation rate, overall vial heat transfer coefficient, and resistance to mass transfer of the dried product are extensively discussed. For all combinations of shelf temperature and chamber pressure studied herein, the highest product temperature, sublimation rate, and overall vial heat transfer coefficient are observed in front edge vials, whereas the lowest values are observed in center vials. In general, the highest sublimation rate, at a given product temperature, is observed for low chamber pressure-high shelf temperature combinations.

Drying Technologies for the Stability and Bioavailability of Biopharmaceuticals

Solid dosage forms of biopharmaceuticals such as therapeutic proteins could provide enhanced bioavailability, improved storage stability, as well as expanded alternatives to parenteral administration. Although numerous drying methods have been used for preparing dried protein powders, choosing a suitable drying technique remains a challenge. In this review, the most frequent drying methods, such as freeze drying, spray drying, spray freeze drying, and supercritical fluid drying, for improving the stability and bioavailability of therapeutic proteins, are discussed. These technologies can prepare protein formulations for different applications as they produce particles with different sizes and morphologies. Proper drying methods are chosen, and the critical process parameters are optimized based on the proposed route of drug administration and the required pharmacokinetics. In an optimized drying procedure, the screening of formulations according to their protein properties is performed to prepare a stable protein formulation for various delivery systems, including pulmonary, nasal, and sustained-release applications.