Freeze-drying Cycle Research Articles

Exploring the potential of a pH-sensitive hydrogel sponge: interpenetrating network of tragacanth and pectin for controlled delivery of levosulpiride.

The development of drug delivery systems that allow precise control over drug release pattern has fetched significant attention in the pharmaceutical field. This research work investigates the potential of a pH-sensitive interpenetrating network (IPN) composed of tragacanth and pectin as a carrier for the controlled release of levosulpiride. To enhance the solubility of poorly soluble drug levosulpiride, inclusion complexes were formed with beta cyclodextrin (βCD). The IPN was prepared by cross-linking tragacanth with pectin by adopting a green chemistry approach. The resulting cross-linked polymeric network was subjected to repetitive freeze-drying cycles for preparation of spongy mass. The physicochemical properties of the resultant product were thoroughly characterized using a range of analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal analyses (DSC/TGA), and X-ray diffraction (XRD). The physical parameters like sol-gel fraction (%), drug loading (%), swelling behavior, electrolyte responsiveness, and in vitro drug release profile of the developed sponge were systematically evaluated under varying pH conditions. Results of FTIR demonstrated the formation of cross-linked network, ruling out drug-excipient interaction. SEM analysis unveiled porous and rough geometry. Thermal analyses proved the hydrogel network thermally stable whereas, PXRD demonstrated the overall amorphous nature of the hydrogel sponge. The outcomes of physical parameters demonstrated an incremental trend in gel fraction from 63 to 85% on raising the molar concentration of cross-linker from TP1 to TP3. However, increasing tragacanth content escalation in gel fraction from 75 to 79% was noticed. While gel fraction was augmented from 79 to 83% with increasing pectin contents. The maximum drug loading formulation TP3 was computed to be 89%. Hydrogel sponges also demonstrated electrolyte responsiveness. The release profile indicated a pH-responsive behavior, with sustained release up to 10h observed in a buffer solution of pH 6.8 and 7.4. In an acidic medium, a minor amount of drug was released during 10h dissolution. Drug release kinetics was observed to be in zero order. The findings of this study highlight the promising potential of the tragacanth/pectin hydrogel sponge as a pH-sensitive dais for the controlled delivery of levosulpiride, emphasizing its potential application in personalized drug therapy and the treatment of gastrointestinal disorders.

Development of a Stable Lyophilized Cyclophosphamide Monohydrate Formulation Using Non-Aqueous Solvents.

To ensure product stability, it is critical to maintain the monohydrate state of cyclophosphamide following lyophilization, as this is the most stable solid form of the Cyclophosphamide. On the other hand, because of their limited aqueous solubility and stability, non-aqueous solvents are preferred for determining the composition and stability of bulk solutions. Hence, the purpose of this study was to use non-aqueous solvents for determining the composition and stability of bulk solutions, and to shorten the lyophilization process by retaining the cyclophosphamide monohydrate. Furthermore, prior to selecting the solvent for the bulk solution consisting of 90:10 tertiary butyl alcohol (TBA) and acetonitrile (ACN), various factors were taken into account, including the freezing point, vapor pressure of solvents, solubility, and stability of cyclophosphamide monohydrate. The concentration of the bulk solution was adjusted to 200mg/mL in order to optimize the fill volume, enhance sublimation rates at lower temperatures during primary drying, and eliminate the need for secondary drying. The differential scanning calorimetry (DSC) measurements of bulk solution were used to improve the lyophilization cycle. The lyophilization cycle opted was freezing at a temperature of -55°C with annealing step at -22°C by which the reconstitution time was significantly reduced. The drying was performed at below - 25°C while maintaining a chamber pressure of 300 mTorr. The complete removal of non-aqueous solvents was achieved by retaining water within the system. The presence of cyclophosphamide monohydrate was confirmed using X-ray diffraction (XRD). The reduction of lyophilization process time was established by conducting mass transfer tests and evaluating the physicochemical properties of the pharmaceutical product. Using non-aqueous solvents for freeze-drying cyclophosphamide is a viable option, and this study provides significant knowledge for the advancement of future generic pharmaceuticals.

Freeze-drying cycle optimization of an amorphous solid dispersion of resveratrol

Resveratrol (RES) has demonstrated advantages as anti-cancer, anti-inflammatory, blood sugar-lowering agent and as cardioprotective agent, among others. Despite RES therapeutic advantages its use in pharmaceutical applications is limited by its low oral bioavailability, mainly due to its poor water solubility. Formulation of poorly water-soluble compound as solid dispersion (SD) converts a crystalline into a more soluble in water amorphous drug. Lyophilization or freeze-drying is a process in which water, an organic solvent, or a co-solvent system is frozen, followed by its removal from the sample, initially by sublimation (primary drying) and then by desorption (secondary drying). This study aimed the development and optimization of a bulk freeze-drying cycle by critical process parameters assessment in each phase to prepare a RES third-generation SD, containing Eudragit E PO as hydrophilic polymer at 1:2 ratio, and Gelucire 44/14 as surfactant at 16 % (w/w) to RES, using a tert-butanol (TBA)/Acetate buffer pH 4.5 (75:25) co-solvent system. A RES third-generation SD with good appearance, not cracked, collapsed, or melted was prepared by an optimized and robust bulk lyophilization process. A physicochemical characterization confirmed the conversion of RES to the amorphous state in the SD and formulation stability after 1 month at 40 °C/75 % RH. Increased solubility and higher dissolution rate compared with pure RES were also obtained.

Chitosan aerogel loaded with biogenic palladium nanoparticles CH/Pd NPs exert antibacterial activity and wound addressing application in vitro and in vivo against bacterial skin infections

Bacterial skin infections that infect wounds and burns are considered one of the most serious medical problems that lead to delay wound healing, toxicity and even death. Therefore, there is an urgent need to develop an effective pharmaceutical material that promotes the treating of skin bacterial infections. Within this, we aimed in this study to synthesis and assess the effectiveness of novel chitosan/palladium nanoparticles (CH/Pd NPs) aerogel composites in treating bacterial skin infections and wound healing. Green method was employed for synthesis of Pd NPs using Allium sativum (A. sativum) extract, while crosslinking process and freeze-drying cycle were utilized for preparation of CH/Pd NPs aerogel composites. The prepared Pd NPs and CH/Pd NPs aerogel composite were thoroughly characterized using UV–vis, FTIR, XRD and SEM. The GC–MS analysis revealed that the main components in the A. sativum were diallyl disulfide (55.88 %) and diallyl trisulfide (24.34 %) which were among the four identified components. Additionally, the total phenols and flavonoids contents were 61.3 mg GAE/100 g and 18.8 mg QE/100 g, respectively. The swelling capacity of CH/Pd NPs aerogel microspheres reach 400 % with blood compatibility and slightly hemolysis ratio about 0.4 %. In vitro, the antibacterial studies demonstrated that loading Pd NPs with CH aerogel microspheres enhanced their effectiveness against MDR bacteria with complete inhibition for all bacterial strains growth. The CH/Pd NPs aerogel microspheres exhibited a significant inhibitory effect on biofilm formation. The biofilm inhibition percentage was found to be 87 % against the biofilm of S. aureus and 80 % against the biofilm of P. aeruginosa. In vivo infection model in rats, CH and CH/Pd NPs aerogel films stimulated skin tissue formation and healing wounds completely in 6 days with highly reduced in MDR and biofilm producing bacterial count. Finally, CH/Pd NPs aerogel composites represent a promising therapeutic strategy for the effective and enhanced healing of infected wounds.

Demystifying Fogging in Lyophilized Products: Impact of Pharmaceutical Processing

A commonly encountered challenge with freeze-dried drug products is glass vial fogging. Fogging is characterized by a thin layer of product deposited upon the inner surface of the vial above the lyophilized cake. While considered to be a routine cosmetic defect in many instances, fogging around the shoulder and neck of the vial may potentially impact container closure integrity and reject rates during inspection. In this work, the influence of processing conditions i.e. vial pre-treatment, lyophilization cycle modifications and filling conditions on fogging was evaluated. A battery of analytical techniques was employed to investigate factors affecting glass vial fogging. A fogging score was used to quantify its severity in freeze-dried products. Additionally, a dye-based method was used to study solution upcreep (Marangoni flow) following product filling. Our lab-scale results indicate measurable improvement in fogging following the addition of an annealing step in the lyophilization cycle. Pre-freeze isothermal holding of the vials (at 5°C on the lyophilizer shelf) for an extended duration indicated a reduction in fogging whereas an increase in the freezing time exhibited no effect on fogging. Vial pre-treatment conditions were critical determinants of fogging for Type 1 vials whereas they had no impact on fogging in TopLyo® vials. The headspace relative humidity (RH) investigation also indicated sufficient increase in the water vapor pressure inside the vial to be conducive to the formulation of a hydration film - the precursor to Marangoni flow.

A Simple and Cost-Effective Technique to Monitor the Sublimation Flow During Primary Drying of Freeze-Drying Using Shelf Inlet/Outlet Temperature Difference or Chamber to Condenser Pressure Drop

As lyophilization continues to be a critical step in the manufacturing of sensitive biopharmaceuticals, challenges often arise during the scale up to commercial scale or the transfer from one manufacturing site to another. While data from the small-scale development of the lyophilization cycle is abundant it is typically much more difficult to extract important information from commercial scale cycles, due to the lack of process analytical technologies available on the commercial line. There is often a reluctance to include wireless temperature or pressure probes during GMP operations due to the additional contamination risk, and retrofitting equipment such as the TDLAS can be prohibitively expensive. Further, as products become more advanced, the cost of consuming the product or even the availability of material may limit the opportunities to run commercial scale trials. This paper presents two novel methods to garner critical cycle information to allow for the evaluation of cycle performance without the need for expensive analytical equipment, costly revalidation and line downtime. Critically, this can be achieved using commonly available temperature and capacitance probes on existing commercial scale equipment. The first method is a calorimetric method, based on quantifying the differences in heat transfer liquid temperature between the shelf inlet and shelf outlet. This change in temperature results from the on-going sublimation, an endo-thermic reaction occurring during lyophilization. The second method uses the differential pressure between the chamber and condenser resulting from the vapor flow from vial to condenser during primary drying. As stated by the authors both methods align well and provide valuable cycle characterization data.

The effect of the mitochondrial-directed antioxidant Mito-TEMPO on the quality of rooster sperm in the cryopreservation and lyophilization cycle

In reproductive technologies applied in animal husbandry, using lyophilized semen is only possible with ICSI technology, due to complete loss sperm motility. However, the anatomical structure’s peculiarities and development of avian oocyte not allows use this technology. Strategies aimed at preserving kinetic apparatus of lyophilized sperm are the most relevant for birds. Increasing mitochondrial activity of cells due to its connection with energy metabolism and sperm motility may be one of the ways to solve this problem. However, similar studies on freeze-dried bird semen haven’t been conducted on this moment. The present study assessed effect of mitochondria-targeted antioxidant Mito-TEMPO on viability, mitochondria’s membrane potential and generation of intracellular hydrogen peroxide by rooster spermatozoa in a cryopreservation and lyophilization cycle. Proportion of cells with intact plasma membrane in lyophilized semen was higher using extenders containing an antioxidant. Addition of Mito-TEMPO at concentration of 40 µM to diluents T-20 and T-30 for the purpose of cryopreservation of semen with subsequent freezedrying allowed to increase proportion of cells with intact plasma membrane in lyophilized semen in comparison to control diluents (6.12 ± 0.11 % versus 10.19±0.46% and 13.19±1.30% versus 15.23±1.13%, respectively, p˂0.05). Effective concentration of Mito-TEMPO in diluents intended only for semen cryopreservation was significantly lower - 5 µM. Proportion of cells with intact plasma membrane was 47,97±0,64% versus 55,85±1,69% and 47,25±2,97% versus 63,21±1,78%, respectively, p˂0, 05. Dose-dependent effect of trehalose in cryoprotective diluents has been proven.

Freeze-drying revolution: unleashing the potential of lyophilization in advancing drug delivery systems.

Lyophilization also known as freeze-drying is a technique that has been employed to enhance the long-term durability of nanoparticles (NPs) that are utilized for drug delivery applications. This method is used to prevent their instability in suspension. However, this dehydration process can cause stress to the NPs, which can be alleviated by the incorporation of excipients like cryoprotectants and lyoprotectants. Nevertheless, the freeze-drying of NPs is often based on empirical principles without considering the physical-chemical properties of the formulations and the engineering principles of freeze-drying. For this reason, it is crucial to optimize the formulations and the freeze-drying cycle to obtain a good lyophilizate and ensure the preservation of NPs stability. Moreover, proper characterization of the lyophilizate and NPs is of utmost importance in achieving these goals. This review aims to update the recent advancements, including innovative formulations and novel approaches, contributing to the progress in this field, to obtain the maximum stability of formulations. Additionally, we critically analyze the limitations of lyophilization and discuss potential future directions. It addresses the challenges faced by researchers and suggests avenues for further research to overcome these limitations. In conclusion, this review is a valuable contribution to the understanding of the parameters involved in the freeze-drying of NPs. It will definitely aid future studies in obtaining lyophilized NPs with good quality and enhanced drug delivery and therapeutic benefits.

Practical Advice on Scientific Design of Freeze-Drying Process: 2023 Update

ObjectiveThe purpose of this paper is to re-visit the design of three steps in the freeze-drying process, namely freezing, primary drying, and secondary drying steps. Specifically, up-to-date recommendations for selecting freeze-drying conditions are provided based on the physical–chemical properties of formulations and engineering considerations.Methods and ResultsThis paper discusses the fundamental factors to consider when selecting freezing, primary drying, and secondary drying conditions, and offers mathematical models for predicting the duration of each segment and product temperature during primary drying. Three simple heat/mass transfer primary drying (PD) models were tested, and their ability to predict product temperature and sublimation time showed good agreement. The PD models were validated based on the experimental data and utilized to tabulate the primary drying conditions for common pharmaceutical formulations, including amorphous and partially crystalline products. Examples of calculated drying cycles, including all steps, for typical amorphous and crystalline formulations are provided.ConclusionsThe authors revisited advice from a seminal paper by Tang and Pikal (Pharm Res. 21(2):191-200, 2004) on selecting freeze-drying process conditions and found that the majority of recommendations are still applicable today. There have been a number of advancements, including methods to promote ice nucleation and computer modeling for all steps of freeze-drying process. The authors created a database for primary drying and provided examples of complete freeze-drying cycles design. The paper may supplement the knowledge of scientists and formulators and serve as a user-friendly tool for quickly estimating the design space.

Possibilities and limitations of α-relaxation data of amorphous freeze-dried cakes to predict long term IgG1 antibody stability

The value of correlating global α-relaxations with long term protein stability after freeze-drying is inconsistently reported. This study aims to clarify whether and to what extend the long term stability of a freeze-dried protein formulation can be predicted with this method. For this purpose, the α-relaxation parameter τβ [h] of freshly prepared freeze-dried products is obtained by isothermal microcalorimetry. The concept is, that molecular movements in the amorphous matrix are strongly reduced in cakes with longer relaxation time and the product should therefore be more resistant against aggregation. To increase τβ in comparison to a conventional freeze-drying cycle, aggressive drying cycles including structural collapse of the product as well as tempering protocols after freeze-drying are applied. The τβ values are correlated with the aggregation rate of a freeze-dried IgG1 monoclonal antibody measured with high performance size exclusion chromatography. The antibody was used in its market formulation and 6 further compositions. A weak correlation between α-relaxation times and IgG1 aggregation was found. A higher mobility level through increased residual moisture helped to improve the correlation.

Heat Flux Analysis and Assessment of Drying Kinetics during Lyophilization of Fruits in a Pilot-Scale Freeze Dryer.

Vacuum freeze-drying as a process for achieving high product quality has attracted increasing attention in the last decade. Particularly in the pharmaceutical field and food processing industries, lyophilization can produce high-quality products compared to samples dried by conventional methods. Despite its benefits, lyophilization is a time-consuming and costly process that requires optimization of a number of process parameters, including shelf temperature, chamber pressure, freezing rate, and process time. This paper reports on the implementation of heat flux measurements that allow noninvasive real-time determination of the endpoint of the primary drying stage as an essential parameter for the effective optimization of the overall drying time. Quantitative analysis of the drying kinetics of five fruits (kiwifruit, avocado, Asian pear, persimmon, and passion fruit) was assessed by comparing the heat flux and temperature profiles of samples during the lyophilization process. For a 24 h lyophilization cycle, average heat fluxes in the primary drying phase ranged from 250 to 570 W/m2. A significant correlation was found between the temperature and heat flux distributions at the estimated endpoint of the sublimation process and the corresponding transition into the secondary drying stage. Furthermore, good agreement was also found for the freezing phase. The use of real-time heat flux measurements proved to be a cost-effective experimental method to better understand the process variables in order to reduce the lyophilization cycle time and overall energy consumption.

Lyophilization cycle design for highly concentrated protein formulations supported by micro freeze-dryer and heat flux sensor

High-concentration protein formulations (HCPFs) represent a common strategy and freeze-drying can mitigate the stability challenges of HCPFs. In general, an in-depth characterization of the lyophilization process is essential to not impair the product quality by inappropriate process parameters. The aim of this study was to create a primary drying design space for lyophilized HCPFs by utilizing the heat flux sensor (HFS) integrated in a MicroFD with a minimum number of cycles and product vials. All the necessary data to obtain the design space were determined starting from only two lyophilization cycles, each holding 19 vials. The vial heat transfer coefficient (Kv) was determined by the HFS and compared to gravimetric values. The results indicate a consistant offset between the HFS and the gravimetry based values for annealed samples with higher protein content. This work highlights a possibility of integrating new technologies, the HFS and the MicroFD to generate a design space for lyophilization of HCPFs, which enables to implement a QbD approach at minimal material and time investment.

State diagram of whole milk for freeze-drying application

The state diagram is a key parameter when optimizing a freeze-drying cycle, as it allows us to set the optimum processing temperature for a specific product. The purpose of this work is to provide some thermodynamic and physicochemical data for optimizing the freeze-drying cycle of whole milk. Freezing point measurements were determined using differential scanning calorimetry and cryoscopy methods, and glass transitions were evaluated by DSC. The endothermic peak was used as the equilibrium freezing point, a variation from 273.93 K to 264.92 K was detected when the dry matter content varied from 0 to 75%. Tg midpoint temperature was used as glass transition of dry mater. Furthermore, Fox and Gordon-Taylor equations were used to predict the glass transition curve to determine Tg', this temperature was used as an approximation of the critical temperature Tc. Collapse temperature was determined using the freeze-drying microscopy setup.

A New Model-Based Approach for the Development of Freeze-Drying Cycles Using a Small-Scale Freeze-Dryer

This paper presents a model-based approach for the design of the primary drying stage of a freeze-drying process using a small-scale freeze-dryer (MicroFD® by Millrock Technology Inc.). Gravimetric tests, coupled with a model of the heat transfer to the product in the vials that account also for the heat exchange between the edge vials and the central vials, are used to infer the heat transfer coefficient from the shelf to the product in the vial (Kv), that is expected to be (almost) the same in different freeze-dryers. Differently from other approaches previously proposed, the operating conditions in MicroFD® are not chosen to mimic the dynamics of another freeze-dryer: this allows saving time and resources as no experiments are needed in the large-scale unit, and no additional tests in the small-scale unit, apart from the three gravimetric tests usually needed to assess the effect of chamber pressure on Kv. With respect to the other model parameter, Rp, the resistance of the dried cake to mass transfer, it is not influenced by the equipment and, thus values obtained in a freeze-dryer may be used to simulate the drying in a different unit, provided the same filling conditions are used, as well as the same operating conditions in the freezing stage, and cake collapse (or shrinkage) is avoided. The method was validated considering ice sublimation in two types of vials (2R and 6R) and at different operating conditions (6.7, 13.3 and 26.7 Pa), with the freeze-drying of a 5% w/w sucrose solution as a test case. An accurate estimate for both Kv and Rp was obtained with respect to the values obtained in a pilot-scale equipment, determined through independent tests for validation purposes. Simulation of the product temperature and drying time in a different unit was then possible, and results were validated experimentally.

Study and optimization of formulation parameters during freeze–drying cycles of model probiotic: Morphology characterization of lyophilisates by scanning electron microscopy

These experimental data are concerning the optimization of freeze-drying cycles of a model-type Casei probiotic bacteria with water based formulations using lactose and polymer polyvinylpyrrolidone (PVP) as cryo-/lyo-protectants. After a previous study devoted to the influence of the main freeze-drying parameters (freezing rates; shelf temperature; absolute pressure) on the bacteria survival ratios, this paper reports some morphological data obtained by scanning electron microscopy (SEM) with the final lyophilisates. The numerous and original SEM images realized with different formulations of water binary or ternary mixtures with fixed operating conditions proved to be very useful to explain and to understand the different bacteria survival ratios observed. Thus, with bacteria or micro-organisms systems, this powerful investigation method of characterization of lyophilisates morphology should be more largely used in the future for setting up the optimal formulations parameters (composition) and the connected operating physical parameters of freeze-drying steps (freezing rate, shelf temperature, absolute pressure).

A model-based optimization strategy to achieve fast and robust freeze-drying cycles

Freeze-drying is a time and cost-intensive process. The primary drying phase is the main target in a process optimization exercise. Biopharmaceuticals require an amorphous matrix for stabilization, which may collapse during primary drying if the critical temperature of the formulation is exceeded. The risk of product collapse should be minimized during a process optimization to accomplish a robust process, while achieving an economical process time. Mechanistic models facilitate the search for an optimal primary drying protocol. We propose a novel two-stage shelf temperature optimization approach to maximize sublimation during the primary drying phase, without risking product collapse. The approach includes experiments to obtain high-resolution variability data of process parameters such as the heat transfer coefficient, vial dimensions and dried layer resistance. These process parameters variability data are incorporated into an uncertainty analysis to estimate the risk of failure of the protocol. This optimization approach enables to identify primary drying protocols that are faster and more robust than a classical approach. The methodology was experimentally verified using two formulations which allow for either aggressive or conservative freeze-drying of biopharmaceuticals.

Lyophilization scale-up to industrial manufacturing: A modeling framework including probabilistic success prediction

Scaling-up a lyophilization cycle to the manufacturing scale successfully at the first pass is of crucial importance to the bio-pharmaceutical community in order to save expensive and sparsely available drug products for clinical and industrial manufacturing. The constraints on time, cost and energy consumption during process development are prohibitive to performing multiple experimental studies at the manufacturing scale. Most process analytical techniques to obtain cycle data are often not available at the manufacturing scale due to sterility concerns with intrusive tools and experimental uncertainties at industrial manufacturing scales. Modeling techniques offer an attractive alternative solution under these circumstances to gain knowledge about the manufacturing scale equipment limitations and predict the probability of success prior to performing experimental trials in order to minimize the risk associated with scale-up. In this paper, we present a detailed characterization of equipment capability curves for lyophilizers across laboratory, pilot and manufacturing scales using Computational Fluid Dynamics (CFD) modeling and highlight the flow features in manufacturing-scale equipment with different geometric attributes. We present the equipment, process and product parameters which determine the outcome of the cycle and develop guidelines for robust scale-up practices from the laboratory and pilot scales to the manufacturing scale using vial heat and mass transfer modeling. We present examples of cycles which would seem to scale-up to the manufacturing-scale successfully using a deterministic model but would have a high probability of failure when process excursions, deviations, and input uncertainties are accounted for by applying a Monte-Carlo based probabilistic model. We demonstrate the method to reduce the failure probability and de-risk the scale-up of such processes. We also present the significant reduction in primary drying time that can be achieved by implementing a lyophilization recipe with varying setpoints of chamber pressure and shelf temperature for the primary drying stage in a manufacturing-scale lyophilizer. All the observations from our modeling analyses and example studies indicate that CFD simulations in combination with deterministic and Monte-Carlo based probabilistic vial heat and mass transfer modeling would significantly improve the success of scale-up to industrial lyophilized drug manufacturing.

The graphical design space for the primary drying phase of freeze Drying: Factors affecting the dried product layer resistance

An emerging approach to process development of a lyophilized pharmaceutical product is to construct a graphical design space for primary drying as an aid to process optimization. The purpose of this paper is to further challenge the assumption in earlier work that the maximum values of the resistance of dried product layer, Rp, is approximately constant and is independent of process conditions within the “acceptable” region of the design space. Three model formulations containing bovine serum albumin as the model protein were chosen to represent: (a) an amorphous system, (b) a crystalline system, and (c) a mixed system where both an amorphous and a crystalline component were present. Low temperature differential scanning calorimetry (DSC) and freeze dry microscopy (FDM) experiments were conducted to estimate critical product temperature. A conservative lyophilization cycle was conducted for each formulation to collect mass flow data and individual design spaces were then established. A series of lyophilization cycles were then conducted using process conditions that resided within the individual design space and the resultant product temperature and resistance of dried product layer (Rp) values were compared between the individual cycles within each formulation. The data indicated that the Rp was component dependent with the mannitol formulation exhibiting higher Rp values than the sucrose formulation. Interestingly, when mannitol was retained amorphous, the formulation exhibited a lower Rp, similar to that of the sucrose formulation. The mixed formulation exhibited intermediate Rp values. Crystallization of mannitol is hypothesized to facilitate a decrease in the size of the ice porous structure by making the water vapor flow path tortuous, thereby increasing the Rp of mannitol formulations. Within the “acceptable” zone of the individual design space, Rp was dependent on the process condition with more aggressive shelf temperature cycles resulting in lower Rp. Specific Surface Area measurements of freeze-dried solids demonstrated that more aggressive conditions resulted in smaller surface area. Freeze-dried solids of crystalline formulations consistently exhibited higher specific surface area than the amorphous formulations.

Vial Breakage in Lyophilization- Case Studies from Commercial Manufacturing and Laboratory Studies

Vial breakage during lyophilization reduces yield and can lead to product contamination with glass particulates, personnel interventions during manufacturing and damage to equipment. We present case studies of full-scale commercial lyophilization operations and small-scale laboratory lyophilization studies to understand and mitigate the sources of vial breakage for sterile injectable products.In the first case study, changes to the lyophilization cycle caused the breakage of 11% of the vials. Breakage rates were higher on the top than the bottom shelves and higher for vials on the edges of the shelves than for center vials. Laboratory strain gauge and process parameter ranging studies confirmed the breakage mechanism to be thermal expansion of the frozen plug early in primary drying, the temperature of which was increased by the cycle changes. We postulate that residual heat from steam sterilization coupled with edge effects drove the breakage patterns.In another case study, we reduced breakage from 3.5% to 0.4% in commercial production by changing the freezing temperature from -45°C to -25°C. Laboratory strain gauge studies confirmed reduced incidence and severity of “break-free” / “plugging-off,” which occurs when the frozen plug abruptly detaches from the vial sidewalls as it is cooled well below Tg’.The final case study is a “breakage challenge” study in the lab using higher fill volumes and aggressive drying to challenge the strength of vials. For borosilicate vials, breakage rates were dramatically higher after washing and tunnel depyrogenation in commercial manufacturing compared to vials that were used as received. Corning Valor® vials remained unbreakable even after processing. Tin oxide external coating provided borosilicate vials significant protection against damage from vial processing.These case studies illuminate vial breakage mechanisms, show how small-scale strain gauge and breakage challenge studies can be used to nearly eliminate vial breakage during full-scale commercial lyophilization.

In-Process Vapor Composition Monitoring in Application to Lyophilization of Ammonium Salt Formulations

Quality control is of critical importance in manufacturing of lyophilized drug product, which is accomplished by monitoring the process parameters. The residual gas analyzer has emerged as a useful tool in determination of endpoint for primary and secondary drying in lyophilization process as well as leak detection in vacuum systems. This study presents the application of in situ RGA to quantify outgassing rates of species released from aqueous inorganic and organic ammonium salt formulations throughout the freeze-drying process. The determination of ammonia outgassing conditions aids in ensuring product quality where ammonia release is an indication for loss of co-solvent or degradation of active pharmaceutical ingredients (APIs). Data analysis methods are developed to determine ammonia presence under various process conditions. In-situ real time monitoring of vapor dynamics enables RGA to be used as a tool to characterize counter-ion loss throughout the freeze-drying cycle.