Microwave-Assisted Freeze-Drying: Impact of Microwave Radiation on the Quality of High-Concentration Antibody Formulations.

Microwave-assisted freeze-drying (MFD) offers significant time savings compared to conventional freeze-drying (CFD). While a few studies have investigated the stability of biopharmaceuticals with low protein concentrations after MFD and storage, the impact of MFD on high-concentration monoclonal antibody (mAb) formulations remains unclear. In this study, we systematically examined the effect of protein concentration in MFD and assessed protein stability following MFD, CFD, and subsequent storage using seven protein formulations with various stabilizers and concentrations. We demonstrated that microwaves directly interact with the active pharmaceutical ingredient (API), leading to decreased physical stability, specifically aggregation, in high-concentration antibody formulations. Furthermore, typically used sugar:protein ratios from CFD were insufficient for stabilizing mAbs when applying microwaves. We identified the intermediate drying phase as the most critical for particle formation, and cooling the samples provided some protection for the mAb. Our findings suggest that MFD technology may not be universally applicable to formulations well tested in CFD and could be particularly beneficial for formulations with low API concentrations requiring substantial amounts of glass-forming excipients, such as vaccines and RNA-based products.

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.

100% Control of Controlled Ice Nucleation Vials by Camera-Supported Optical Inspection in Freeze-Drying.

Freeze-drying is the drying technology of choice for sensitive biological drugs. On the one side, it is admired for its suitability for the stabilization of sensitive molecules. On the other side, it is a time-consuming production step posing challenges in process development and technology transfer. The application of controlled ice nucleation is one elegant approach to shorten freeze-drying times significantly and at the same time increase batch homogeneity. However, a reliable 100% control of the controlled nucleation step in each vial is essential, considering the impact of the nucleation temperature on product quality attributes. In this study, we introduce a camera-supported optical inspection method that utilizes the different superficial cake structures seen in controlled and random nucleated lyophilizates. Derived from the grayscale analysis, the new distinguishing criterion "average edge brightness" is introduced. Four different formulations containing Sucrose, Trehalose, and/or bovine serum albumin were freeze dried with random or controlled nucleation and analyzed with the new technology. A proof of concept is provided by the analysis of a similar-to-market lyophilized monoclonal antibody formulation freeze-dried with three different freezing protocols covering different nucleation profiles. For all investigated formulations and process conditions, the clear discrimination of controlled and randomly nucleated vials was possible. By this, the technology allowed for reliable, noninvasive, and automatable 100% monitoring of controlled nucleation success after freeze-drying.

Microwave-Assisted Freeze-Drying of Monoclonal Antibodies: Product Quality Aspects and Storage Stability.

In order to overcome the downside of long conventional freeze-drying (CFD) process times for monoclonal antibody formulations, microwave-assisted freeze-drying (MFD) was introduced. Recently, the general applicability and potential shortening of drying times were shown. However, little is known about the storage stability of MFD products compared to CFD references. Additionally, batch homogeneity issues were seen within MFD in the past. In this study, we examined four different formulations of two different monoclonal antibodies using three different glass-forming excipients: sucrose, trehalose, and arginine phosphate. These formulations were freeze-dried with two different drying protocols (CFD and MFD), stored for 24 weeks, and analyzed for solid-state and protein-related quality attributes. Moreover, a new microwave generator setup was investigated for its potential to improve batch homogeneity. In all investigated formulations, comparable stability profiles were found, although the classical magnetron generator led to inferior batch homogeneity with respect to residual moisture distribution. In contrast, the new MFD setup indicated the potential to approximate batch homogeneity to the level of CFD. However, for future applications, there is an unabated need for new machine designs to comply with pharmaceutical manufacturing requirements.

A Comparison of Controlled Ice Nucleation Techniques for Freeze-Drying of a Therapeutic Antibody.

The aim of this study was to investigate if mechanistically different controlled ice nucleation techniques in freeze-drying are comparable to each other with respect to drying process performance and product quality attributes. Therefore, we studied 3 different model formulations including amorphous (sucrose, trehalose) and semi-crystalline (mannitol:sucrose 4:1) solids containing a monoclonal antibody IgG1 (5 g/L) processed either by application of ice fog or depressurization technique setting an ice nucleation temperature of -5°C. Subsequently, the same freeze-drying protocol on identical machinery was applied. The results showed that the techniques are comparable with respect to the thermal history of product temperature sensors and primary drying time, solid state- and protein-related product quality attributes. All analytics comprising Karl Fischer titration, X-ray powder diffraction and Brunauer-Emmet-Teller as well as high-performance size exclusion chromatography, turbidity and subvisible particle counting using flow-imaging microscopy exhibited similarity and comparability among the controlled nucleation protocols.

Significant Drying Time Reduction Using Microwave-Assisted Freeze-Drying for a Monoclonal Antibody.

Microwave-assisted freeze-drying (MFD) is a rapid drying process well known in food technology. However, little is known about its application to biologicals. In this study, we investigated the applicability and feasibility of this technology to different monoclonal antibody formulations and the influence on the resulting product properties. Moreover, one of our main objectives was to study if significant reductions in drying times could be achieved. In addition, the effect of the drying process on the accelerated stability of a sucrose-based antibody formulation at 40°C and 25°C over 12 weeks was investigated. MFD resulted in drying time reduction >75%. For all model formulations, cake appearance and solid state properties were found to be comparable to standard lyophilized products. These formulations covered a wider range of lyophilization excipients comprising sucrose and trehalose, semi-crystalline forming solids like mannitol:sucrose mixtures and others like arginine phosphate and a mixture of 2-hydroxypropyl-ß-cyclodextrin with sucrose. Moreover, comparable low changes in relative monomer content, the relative amount of soluble aggregates and cumulative particles ≥1 µm per mL were observed over 12 weeks of storage, regardless of the drying technology. This makes MFD a promising innovative alternative for the rapid production of freeze-dried biologicals while maintaining product quality.

Lyophilized Drug Product Cake Appearance: What Is Acceptable?

Cake appearance is an important attribute of freeze-dried products, which may or may not be critical with respect to product quality (i.e., safety and efficacy). Striving for "uniform and elegant" cake appearance may continue to remain an important goal during the design and development of a lyophilized drug product. However, "sometimes" a non-ideal cake appearance has no impact on product quality and is an inherent characteristic of the product (due to formulation, drug product presentation, and freeze-drying process). This commentary provides a summary of challenges related to visual appearance testing of freeze-dried products, particularly on how to judge the criticality of cake appearance. Furthermore, a harmonized nomenclature and description for variations in cake appearance from the ideal expectation of uniform and elegant is provided, including representative images. Finally, a science and risk-based approach is discussed on establishing acceptance criteria for cake appearance.

Can controlled ice nucleation improve freeze-drying of highly-concentrated protein formulations?

The aim of this study was to investigate if controlled ice nucleation with our previouly published method is applicable to highly-concentrated protein formulations of bovine serum albumin (100 mg/ml and 193.9 mg/ml) and a monoclonal antibody (161.2 mg/ml) and if positive effects on primary drying time as well as reconstitution times can be achieved. We observed that for both proteins, ice nucleation at a product temperature of -5 °C significantly reduced primary drying time. Furthermore, reconstitution times of the lyophilized cakes could be shortened, especially for the monoclonal antibody formulation with a reconstitution time of 5 minutes instead of 15 minutes.

Pharmaceutical feasibility of sub-visible particle analysis in parenterals with reduced volume light obscuration methods.

The draft for a new United States Pharmacopoeia (USP) monograph {787} "Sub-visible Particulate Matter in Therapeutic Protein Injections" describes the analysis of sub-visible particles by light obscuration at much lower sample volumes as so far required by the European Pharmacopoeia (Ph. Eur.) and the USP for parenterals in general. Our aim was to show the feasibility of minimizing the sample expenditure required for light obscuration similar to the new USP settings for standards and pharmaceutically relevant samples (both proteins and small molecules), without compromising the data quality. The light obscuration method was downscaled from >20 ml volume as so far specified in Ph. Eur./USP to 1 ml total sample volume. Comparable results for the particle concentration in all tested size classes were obtained with both methods for polystyrene standards, stressed BSA solutions, recombinant human IgG1 formulations, and pantoprazol i.v. solution. An additional advantage of the low volume method is the possibility to detect vial-to-vial variations, which are leveled out when pooling several vials to achieve sufficient volume for the Ph. Eur./USP method. This is in particular important for biotech products where not only the general quality aspect, but also aggregate formation of the drug substance is monitored by light obscuration.

Protein stabilization by cyclodextrins in the liquid and dried state.

Aggregation is arguably the biggest challenge for the development of stable formulations and robust manufacturing processes of therapeutic proteins. In search of novel excipients inhibiting protein aggregation, cyclodextrins and their derivatives have been under examination for use in parenteral protein products since more than 20 years and significant research work has been accomplished highlighting the great potential of cyclodextrins as stabilizers of therapeutic proteins. Oftentimes, the potential of cyclodextrins to inhibit protein aggregation has been attributed to their capability to incorporate hydrophobic residues on aggregation-prone proteins or on their partially unfolded intermediates into the hydrophobic cavity. In addition, also other mechanisms besides or even instead of complex formation play a role in the stabilization mechanism, e.g. non-ionic surfactant-like effects. In this review a comprehensive overview of the available research work on the beneficial use of cyclodextrins and their derivatives in protein formulations, liquid as well as dried, is provided. The mechanisms of stabilization against different kinds of stress conditions, such as thermal or surface-induced, are discussed in detail.