Best Practices and Guidelines (2022) for Scale-up and Technology Transfer in Freeze Drying Based on Case Studies. Part 2: Past Practices, Current Best Practices, and Recommendations

Impact of vial quality on interactions, particle formation, container closure integrity, and gas permeability for frozen drug product storage

The frozen storage of biopharmaceuticals brings new challenges to the primary packaging material. Due to an increasing demand and the downsides of standard type I glass vials, such as vial breakage, novel vial types for special applications of parenteral drug products have been introduced to the market in the past years. Mechanical stresses due to dimensional changes experienced during freezing and thawing could change the material properties, hence affecting the interaction with the drug product stored in the vial or functionality such as overall integrity. Therefore, we studied the suitability of different vial qualities related to the thermally induced mechanical stresses experienced during frozen drug product preparation and storage. First, the possible failure modes for each vial type were identified. The interaction between vial surface and drug product were investigated considering surface hydrophobicity, surface free energy and surface roughness as well as microscopically visible changes analyzed by confocal laser scanning microscopy. Differences in surface hydrophobicity, roughness and surface free energy between the vial types did not impact the performance upon freeze-thaw stress and did not change with the stress. Screening the vial content for particles originating from the container using light and electron scanning microscopy combined with energy-dispersive X-ray spectroscopy showed only rare cases of particles in coated glass vials. Under extreme stress conditions, including a drop-test in the frozen state, a low number of particles was also detected in coated polymer vials. No quality issues regarding the functionality were observed upon container closure integrity testing, while the oxygen permeability was slightly increased for uncoated and especially coated polymer vials. Overall, the results show that several vial types are appropriate for the frozen storage of drug products and selection should be based on the formulation and other product requirements.

Obtaining heat transfer coefficients (Kv) distribution directly from mass flow measurements during the sublimation step of freeze-drying

The knowledge of heat transfer coefficients (Kv) and their distribution is a crucial element in the successful transfer of a freeze-drying process to a new piece of equipment. Nevertheless, the implementation of the classical ice sublimation method is resource consuming, particularly in the industrial context, which represents a significant barrier to its application. This paper demonstrates that the Kv distribution can be calculated from the measurement of mass flow during a freeze-drying operation by reversing the results of process simulation calculations. This methodology works independently of the experimental method used to measure the mass flux: tunable diode laser absorption, inlet/outlet temperature difference of the shelves, or chamber/ condenser pressure difference. The advantage of this new method is that it requires no specific experimental effort and can be carried out on routine production runs (especially with the temperature or pressure difference methods), provided the freeze drier possesses at least shelf inlet/outlet temperature measurement and/or chamber and condenser capacitance pressure measurement. Furthermore, the measurement encompasses all vials, which is not achievable using the conventional method for commercial units that contain tens of thousands of vials. Once fed back into the primary drying mechanistic model, the Kv distribution is used to estimate the temperature distribution in the product. In this article, we provide practical examples at all scales, from laboratory to industrial production.

Scaling up controlled nucleation in freeze drying: Translating vacuum-induced surface freezing from laboratory to GMP

The freezing step often causes batch inhomogeneity and issues during freeze drying process transfer. The nucleation temperature at which the first ice is formed during freezing differs from vial to vial, and significantly between scales. To solve this issue, Controlled Ice Nucleation techniques can be applied to induce ice nucleation at a defined product temperature across the whole batch. This study describes the application of vacuum-induced surface freezing (VISF) for a therapeutic antibody formulation, including the process transfer from laboratory scale through pilot scale to a GMP line. The VISF method could be successfully implemented on all scales of freeze dryers without equipment adaptation. Some scale-dependent changes in pressure control and degassing were necessary to achieve nucleation in all vials and avoid defects. The resulting lyophilized products were characterized and further analyzed in a stability study. While most critical quality attributes were comparable for product manufactured with and without Controlled Nucleation, the appearance of cakes processed using VISF was much better, which could be linked to different product morphology due to freeze-concentration. The results of this study allow direct comparison of the application of controlled nucleation for an antibody formulation at different scales and confirm the applicability of the technology.

Importance of Kv Distribution in Freeze Drying: Part II: Use in Lyo Simulation Modeling

This article is the second of a series of two articles. In the first article of the series, a new Kv distribution model and an experimental methodology to measure the Kv distribution were introduced. In this second part, the Kv distribution is integrated into a lyo-simulation tool, to more accurately predict the variability of the product temperature, primary drying time, total sublimation mass flow and Pirani signal. The Kv distribution is also integrated into the graphical design space. The impact of incorporating the Rp distribution is briefly discussed. The comparison of the simulation tool with actual product temperature monitoring, Pirani signal or overall sublimation flow shows very good agreement in the case studies presented. Overall, the lyo-simulation incorporating the Kv distribution is a very useful tool to support industrial development, i.e. process optimization, scale assessment, technology transfer, and troubleshooting of the lyophilization process.

Establishing a Multi-Vial Design Space for the Freeze-Drying Process by Means of Mathematical Modeling of the Primary Drying Stage

Primary drying is the most critical stage of the freeze-drying process. This work aimed to establish a design space for this process by means of mathematical modeling of the primary drying stage, capable of addressing the thermal characteristics of distinct vial suppliers. Modeling of primary drying was implemented on Microsoft Excel using steady-state heat and mass transfer equations at two extreme conditions as assessed by risk analysis, to predict product temperature and primary-drying time. The heat transfer coefficients (Kv) of four different vial suppliers were experimentally determined, both, at the center and edge of the freeze-dryer's shelf. Statistically significant differences (ANOVA p<0.05) were observed between suppliers throughout the assessed pressure range. Overall, the average Kve/Kvc (edge/center) ratio was higher than 1.6 for all suppliers due to the radiation effect. A design space for the drying process was established using mathematical modeling taking into account the Kv of the worst-case supplier, in the shelf edge. A primary drying cycle was carried out at a shelf temperature of -25 °C and a chamber pressure of 45 mTorr for 8 % sucrose and at -10 °C and 75 mTorr for 5 % NaCl. Freeze-dried products with good cosmetic appearance were obtained for the four vial suppliers both, in the shelf center and edge. The results show that it is possible to predict and establish the critical parameters for the primary drying stage, under a design space concept, considering the differences in the Kv of vial suppliers without adverse consequences on the quality of the finished freeze-dried product.

Roadmap for Drug Product Development and Manufacturing of Biologics

Therapeutic biology encompasses different modalities, and their manufacturing processes may be vastly different. However, there are many similarities that run across the different modalities during the drug product (DP) development process and manufacturing. Similarities include the need for Quality Target Product Profile (QTTP), analytical development, formulation development, container/closure studies, drug product process development, manufacturing and technical requirements set out by numerous regulatory documents such as the FDA, EMA, and ICH for pharmaceuticals for human use and other country specific requirements. While there is a plethora of knowledge on studies needed for development of a drug product, there is no specific guidance set out in a phase dependent manner delineating what studies should be completed in alignment with the different phases of clinical development from pre-clinical through commercialization. Because of this reason, we assembled a high-level drug product development and manufacturing roadmap. The roadmap is applicable across the different modalities with the intention of providing a unified framework from early phase development to commercialization of biologic drug products.

Impact of Controlled Ice Nucleation and Lyoprotectants on Nanoparticle Stability during Freeze-drying and upon Storage

The freezing step of the lyophilization process can impact nanoparticle stability due to increased particle concentration in the freeze-concentrate. Controlled ice nucleation is a technique to achieve uniform ice crystal formation between vials in the same batch and has attracted increasing attention in pharmaceutical industry. We investigated the impact of controlled ice nucleation on three types of nanoparticles: solid lipid nanoparticles (SLNs), polymeric nanoparticles (PNs), and liposomes. Freezing conditions with different ice nucleation temperatures or freezing rates were employed for freeze-drying all formulations. Both in-process stability and storage stability up to 6 months of all formulations were assessed. Compared with spontaneous ice nucleation, controlled ice nucleation did not cause significant differences in residual moisture and particle size of freeze-dried nanoparticles. The residence time in the freeze-concentrate was a more critical factor influencing the stability of nanoparticles than the ice nucleation temperature. Liposomes freeze-dried with sucrose showed particle size increase during storage regardless of freezing conditions. By replacing sucrose with trehalose, or adding trehalose as a second lyoprotectant, both the physical and chemical stability of freeze-dried liposomes improved. Trehalose was a preferable lyoprotectant than sucrose to better maintain the long-term stability of freeze-dried nanoparticles at room temperature or 40°C.