Effects of temperature ramp rate during the primary drying process on the properties of amorphous-based lyophilized cake, Part 1: Cake characterization, collapse temperature and drying behavior

Pore shape matters - In-situ investigation of freeze-drying kinetics by 4D XCT methods

Freeze-drying is a commonly employed method in the food industry to extend shelf life of products. However, this process remains time and energy consuming. While higher shelf temperatures accelerate the process, they also pose the risk of product damage. The microstructure of the product, influencing heat and mass transport, is a critical factor. This study aims to understand the impact of 3-dimensional (3D) structural parameters (pore size, shape and orientation) on local primary freeze-drying kinetics. Freeze-drying experiments were conducted with maltodextrin solutions (c1 = 0.05, c2 = 0.15 and c3 = 0.3 w/w) at different shelf temperatures (T1 = -11, T2 = -15 and T3 = -33 °C) with the use of a freeze-drying stage that allows in-situ visualization of the process inside a 4D-X-Ray computed tomography (XCT). The findings show the importance of understanding the microstructure in detail to optimize the sublimation time during the freeze-drying process. It is shown that for longitudinal pores, the orientation is a crucial parameter.

Freezing process influences cake appearance of a lyophilized amorphous protein formulation with low solid content and high fill configuration

Low solid content and high fill drug product configuration pose special challenges for achieving elegant cake appearance after lyophilization. In this study, such a configuration for a protein formulation required lyophilization within a narrow primary drying operating space to obtain elegant cakes. Freezing process optimization was explored as a solution. A Design of Experiment (DoE) approach was used to evaluate the effect of shelf cooling rate, annealing temperature, and their interaction on cake appearance. The slope of product resistance (R_p) vs. dried layer thickness (L_dry) was used as the quantitative response because elegant cake appearance correlated with a lower initial R_p and positive slope. As the R_p vs. L_dry slope can be experimentally established within the first 1/6th of the total primary drying duration, partial lyophilization runs were executed, allowing for rapid screening. The DoE model revealed that a slow cooling rate (≤0.3 °C/min) and high annealing temperature (≥-10 °C) resulted in a better cake appearance. Furthermore, X-ray micro-computed tomography showed that elegant cakes exhibited uniform porous structure and larger pores, while inelegant cakes showed dense top layers with smaller pores. With the optimized freezing process, the primary drying operating space was broadened with improved cake appearance and batch homogeneity.

Long-Circulating and Fusogenic Liposomes Loaded with Paclitaxel and Doxorubicin: Effect of Excipient, Freezing, and Freeze-Drying on Quality Attributes

Liposomes can increase plasma half-life, enhance targeting, and diminish the side-effects of loaded drugs. On the downside, physical and chemical instabilities of dispersions often result in a reduced lifespan, which limits their availability on the market. Solid formulations obtained by freeze-drying can immobilize vesicles and provide extended shelf life. For both processes, the choice of excipients and process parameters are crucial to protect the carrier layers against tension caused by freezing and/or dehydration. The aim of this work is to evaluate the influence of freezing and drying parameters, besides excipient choice, to obtain solid long-circulating and fusogenic liposomes (LCFL-PTX/DXR) co-encapsulating paclitaxel (PTX) and doxorubicin (DXR) at a synergistic ratio (1:10).

METHODS

LCFL-PTX/DXR was evaluated by freeze-drying microscopy (glass transition, Tg'), differential scanning calorimetry (collapse temperature, Tc), freeze-thawing and freeze-drying processes. Freeze-dried samples were evaluated by thermogravimetry (residual moisture) and the resuspended liposomes were characterized in terms of size, polydispersity index (PI), zeta potential (ZP), and drug content. Liposomes morphology was evaluated by cryomicroscopy.

RESULTS

Trehalose protected PTX cargo upon freeze-thawing and more than 80% of the original DXR retention. The formulations with trehalose resulted in a cake with 5-7% of moisture content (200-240 nm); 44-60% of PTX retention, and 25-35% of DXR retention, with the variations caused by cryoprotector concentration and process changes.

CONCLUSIONS

Trehalose protected liposome integrity, maintaining PTX retention and most of DXR upon freeze-thawing. Freeze-drying reduced the retention of both drugs inside all liposomes, whereas formulation with trehalose presented minor losses. Therefore, this frozen formulation is an alternative product option, with no need for manipulation before use.

Recent advances and persistent challenges in the design of freeze-drying process for monoclonal antibodies

Monoclonal antibodies constitute nowadays an important therapeutic class and the number of approved molecules for clinical uses continues to increase, achieving considerable part of the therapeutic market. Yet, the stability in solution of these biopharmaceuticals is often low. That's why freeze-drying has been and remains the method of choice to obtain monoclonal antibodies in the solid state and to improve their stability. The design of freeze-drying process and its optimization are still topical subjects of interest and the pharmaceutical industry is regularly challenged by the requirements of quality, safety and efficiency set by the regulatory authorities. These requirements imply a deep understanding of each step of the freeze-drying process, developing techniques to control the critical parameters and to monitor the quality of the intermediate and the final product. In addition to quality issues, the optimization of the freeze-drying process in order to reduce the cycle length is of great interest since freeze-drying is known to be an energy-expensive and time consuming process. In this review, we will present the recent literature dealing with the freeze-drying of monoclonal antibodies and focus on the process parameters and strategies used to improve the stability of these molecules and to optimize the FD process.

The Influence of Local Microstructure Inhomogeneities on Local Drying Kinetics during Freeze-Drying

Freeze-drying is a gentle drying technique to dry high value products, such as pharmaceuticals, without impacting the quality of the product. However, this method is very time and cost intensive. It is known that larger pores reduce the duration of primary drying due to facilitated mass transport. However, next to the pore size, other structural parameters exist whose influence on drying kinetics is still unknown. Therefore, the aim of this article is to investigate the influence of the microstructure (pore size, shape and orientation) on local primary drying kinetics. In the study, freeze-drying experiments on maltodextrin and sucrose solutions (c₁ = 0.05 and c₂ = 0.15 w/w) were carried out in a lyomicroscope. Two-dimensional images were recorded during the whole drying process and in the dry state and analyzed on the movement of the sublimation front, pore size, orientation and shape. Different microstructures were created by using different freezing parameters, namely two different cooling rates and solid concentrations. It could be shown that for pores with a high aspect ratio, the pore orientation was more important for the drying kinetics than the pore size, while for pores with a lower aspect ratio the pore size was the decisive parameter.

Innovative Drying Technologies for Biopharmaceuticals

In the past two decades, biopharmaceuticals have been a breakthrough in improving the quality of lives of patients with various cancers, autoimmune, genetic disorders etc. With the growing demand of biopharmaceuticals, the need for reducing manufacturing costs is essential without compromising on the safety, quality, and efficacy of products. Batch Freeze-drying is the primary commercial means of manufacturing solid biopharmaceuticals. However, Freeze-drying is an economically unfriendly means of production with long production cycles, high energy consumption and heavy capital investment, resulting in high overall costs. This review compiles some potential, innovative drying technologies that have not gained popularity for manufacturing parenteral biopharmaceuticals. Some of these technologies such as Spin-freeze-drying, Spray-drying, Lynfinity® Technology etc. offer a paradigm shift towards continuous manufacturing, whereas PRINT® Technology and Microglassification^TM allow controlled dry particle characteristics. Also, some of these drying technologies can be easily scaled-up with reduced requirement for different validation processes. The inclusion of Process Analytical Technology (PAT) and offline characterization techniques in tandem can provide additional information on the Critical Process Parameters (CPPs) and Critical Quality Attributes (CQAs) during biopharmaceutical processing. These processing technologies can be envisaged to increase the manufacturing capacity for biopharmaceutical products at reduced costs.

Freeze-Drying with Structured Sublimation Fronts—Visualization with Neutron Imaging

The particular structure of the sublimation front in vacuum freeze-drying of porous media is, in most situations, not accessible at the pore scale. The classical measurement techniques access the process only globally. Knowledge about the structure of the front, however, is necessary for prescriptive analysis of freeze-drying, as it dictates not only drying velocity, drying time, and overall energy consumption, but also the material properties after drying. This is especially relevant in situations in which the freeze-drying process is carried out close to the collapse temperature of the product. We, therefore, study the sublimation of ice with neutron tomography and analyze the spatial formation of the dry space using the example of frozen cylindrical maltodextrin with drying parameters at the limit of material collapse. We show that the sublimation front forms unique fractal structures that differ strongly from the usual form of a flat front. Distinct dry fingers covering the sample, in addition to a fractal peripheral sublimation front, were observed. The findings are important for the understanding of freeze-drying processes and will serve as a basis for the development of microscale models of freeze-drying.

Development of freeze-drying cycle via design space approach: a case study on vaccines

Freeze-drying is a dehydration process that provides improved stability of vaccine formulations for shipment and storage. During the primary drying steps of the process, product temperature has to be maintained below a critical value to avoid visual defects of the product, leading to an increase of the sublimation time and thus of the operational costs. In this work, we used the design space approach together with experimental analysis for the development of the primary drying step of a vaccine model formulation. First, the formulation was characterized by determining the glass transition and the collapse temperatures. Successively, the dynamic design space of primary drying was calculated via mathematical modelling, and a proven acceptable range (PAR) was defined around the selected operating values. Finally, the cycle and the PAR were validated by performing a freeze-drying cycle at pilot scale and by evaluating the values of the product critical quality attributes (e.g. moisture content, visual aspect, reconstitution time).

Be Aggressive! Amorphous Excipients Enabling Single-Step Freeze-Drying of Monoclonal Antibody Formulations

Short freeze-drying cycles for biopharmaceuticals are desirable. Formulations containing an amorphous disaccharide, such as sucrose, are prone to collapse upon aggressive primary drying at higher shelf temperature. We used 2-hydroxypropyl-betacyclodextrin (HPBCD) in combination with sucrose and polyvinylpyrrolidone (PVP) to develop an aggressive lyophilization cycle for low concentration monoclonal antibody (mAb) formulations. Glass transition temperature and collapse temperature of the formulations were determined, and increasingly aggressive cycle parameters were applied. Using a shelf temperature of +30 °C during primary drying, the concept of combining sublimation and desorption of water in a single drying step was investigated. Cake appearance was evaluated visually and by micro-computed tomography. Lyophilisates were further analyzed for reconstitution time, specific surface area, residual moisture, and glass transition temperature. We demonstrated the applicability of single-step freeze-drying, shortening the total cycle time by 50% and providing elegant lyophilisates for pure HPBCD and HPBCD/sucrose formulations. HPBCD/PVP/sucrose showed minor dents, while good mAb stability at 10 mg/mL was obtained for HPBCD/sucrose and HPBCD/PVP/sucrose when stored at 40 °C for 3 months. We conclude that HPBCD-based formulations in combination with sucrose are highly attractive, enabling aggressive, single-step freeze-drying of low concentration mAb formulations, while maintaining elegant lyophilisates and ensuring protein stability at the same time.

Science and art of protein formulation development

Protein pharmaceuticals have become a significant class of marketed drug products and are expected to grow steadily over the next decade. Development of a commercial protein product is, however, a rather complex process. A critical step in this process is formulation development, enabling the final product configuration. A number of challenges still exist in the formulation development process. This review is intended to discuss these challenges, to illustrate the basic formulation development processes, and to compare the options and strategies in practical formulation development.