Practical Formulation and Process Development of Freeze-Dried Products

Optimizing the lyophilization of Lumbricus terrestris erythrocruorin

Haemorrhagic shock is a leading cause of death worldwide. Blood transfusions can be used to treat patients suffering severe blood loss but donated red blood cells (RBCs) have several limitations that limit their availability and use. To solve the problems associated with donated RBCs, several acellular haemoglobin-based oxygen carriers (HBOCs) have been developed to restore the most important function of blood: oxygen transport. One promising HBOC is the naturally extracellular haemoglobin (i.e. erythrocruorin) of Lumbricus terrestris (LtEc). The goal of this study was to maximise the portability of LtEc by lyophilising it and then testing its stability at elevated temperatures. To prevent oxidation, several cryoprotectants were screened to determine the optimum formulation for lyophilisation that could minimise oxidation of the haem iron and maximise recovery. Furthermore, samples were also deoxygenated prior to storage to decrease auto-oxidation, while resuspension in a solution containing ascorbic acid was shown to partially reduce LtEc that had oxidised during storage (e.g. from 42% Fe3+ to 11% Fe3+). Analysis of the oxygen equilibria and size of the resuspended LtEc showed that the lyophilisation, storage, and resuspension processes did not affect the oxygen transport properties or the structure of the LtEc, even after 6 months of storage at 40 °C. Altogether, these efforts have yielded a shelf-stable LtEc powder that can be stored for long periods at high temperatures, but future animal studies will be necessary to prove that the resuspended product is a safe and effective oxygen transporter in vivo.

Rational Design, Synthesis, and Characterization of a Solid Δ9-Tetrahydrocannabinol Nanoformulation Suitable for "Microdosing" Applications

Background: This article highlights the formulation of a solid Δ9-tetrahydrocannabinol (THC)-loaded ingestible prepared from pure THC distillate. Methods: A THC-containing ethanol-assisted cannabinoid nanoemulsion (EACNE) was created using a solvent displacement technique. Subsequently, the EACNE was converted to a solid powdery material while still retaining its THC potency, a format uniquely suited for "microdosing" applications. Results: EACNE had an average lipid droplet size of ∼190 nm, with a polydispersity index of 0.15, and an average droplet ζ potential of -49±10 mV. The nanoemulsion (NE) was colloidally stable for at least 6 weeks, with no meaningful change in cannabinoid potency over the experimental period, as determined by high-performance liquid chromatography analysis. The EACNE remained stable when subjected to physical stresses such as heat, freeze/thaw cycles, carbonation, dilution to beverage concentrations, high sucrose concentrations, and a pH range between 5 and 8. The microencapsulated EACNE demonstrated limited free-flowing behavior but was freely redispersible in water without any visible phase separation. Conclusions: We report the design, creation, and characterization of a THC NE generated without the use of specialized equipment, such as a microfluidizer or a high-pressure homogenizer. This emulsion could readily be converted to a water-redispersible powder. This embodiment is particularly suited for THC "microdosing," a practice that might decouple the health benefits of THC from its psychotropic effects.

CMC Strategies and Advanced Technologies for Vaccine Development to Boost Acceleration and Pandemic Preparedness

This review reports on an overview of key enablers of acceleration/pandemic and preparedness, covering CMC strategies as well as technical innovations in vaccine development. Considerations are shared on implementation hurdles and opportunities to drive sustained acceleration for vaccine development and considers learnings from the COVID pandemic and direct experience in addressing unmet medical needs. These reflections focus on (i) the importance of a cross-disciplinary framework of technical expectations ranging from target antigen identification to launch and life-cycle management; (ii) the use of prior platform knowledge across similar or products/vaccine types; (iii) the implementation of innovation and digital tools for fast development and innovative control strategies.

In-situ investigation of solid phase evolution during lyophilization of mannitol-based antibody formulations using an XRPD climate chamber

Crystalline mannitol is commonly used as bulking agent in antibody formulations to provide structure to the lyophilized cake and prevent collapse. Depending on the lyophilization process conditions mannitol can either crystallize as α-, β-, δ-mannitol, mannitol-hemihydrate, or transition to its amorphous state. While crystalline mannitol helps to create a firmer cake structure this is not true for amorphous mannitol. The hemihydrate is also an undesired physical form as it may reduce the drug product stability by releasing bound water molecules into the cake. Our aim was to simulate lyophilization processes in an X-ray powder diffraction (XRPD) climate chamber. In the climate chamber, the process can be carried out fast with low sample quantities to determine optimal process conditions. Insights on the emergence of desired anhydrous mannitol forms helps to adjust the process parameters in larger scale freeze-dryers. In our study we have identified the critical process steps for our formulations and then varied relevant process parameters, which were the annealing temperature, annealing time and temperature ramp rate of the freeze-drying process. Furthermore, the effect of the presence of antibodies on excipient crystallization was investigated by performing the studies on placebo solutions versus two respective antibody formulations. A comparison of the products obtained in a freeze-dryer and the simulated process in the climate chamber showed good accordance demonstrating the method as suitable tool to identify ideal process conditions on a laboratory scale.

Prospects of Inhaled Phage Therapy for Combatting Pulmonary Infections

With respiratory infections accounting for significant morbidity and mortality, the issue of antibiotic resistance has added to the gravity of the situation. Treatment of pulmonary infections (bacterial pneumonia, cystic fibrosis-associated bacterial infections, tuberculosis) is more challenging with the involvement of multi-drug resistant bacterial strains, which act as etiological agents. Furthermore, with the dearth of new antibiotics available and old antibiotics losing efficacy, it is prudent to switch to non-antibiotic approaches to fight this battle. Phage therapy represents one such approach that has proven effective against a range of bacterial pathogens including drug resistant strains. Inhaled phage therapy encompasses the use of stable phage preparations given via aerosol delivery. This therapy can be used as an adjunct treatment option in both prophylactic and therapeutic modes. In the present review, we first highlight the role and action of phages against pulmonary pathogens, followed by delineating the different methods of delivery of inhaled phage therapy with evidence of success. The review aims to focus on recent advances and developments in improving the final success and outcome of pulmonary phage therapy. It details the use of electrospray for targeted delivery, advances in nebulization techniques, individualized controlled inhalation with software control, and liposome-encapsulated nebulized phages to take pulmonary phage delivery to the next level. The review expands knowledge on the pulmonary delivery of phages and the advances that have been made for improved outcomes in the treatment of respiratory infections.

Aspects of Lyophilization of Cardiac Bioimplant

The use of implants of biological origin in clinical practice has led to the search for methods of long-term storage of tissues without damaging their functional and structural characteristics. Xenografts (extracted from pericardium of pigs, horses, bulls) are drawing more and more interest. The bovine pericardium is exposed to chemical and physical factors providing complete purification of tissue from cells and their components. Such scaffolds are protein (collagen) complexes that fully replicate the microstructure of the pericardial tissue. Lyophilisation ensures long-term preservation of the extracellular matrix properties. The principle of the method is in drying pre-frozen tissue, in which water is sublimated. The method is intended for storage, transportation, and the subsequent use of the bioimplant in clinical practice. However, the lyophilization process may be accompanied by various undesirable factors that can lead to denaturation of the matrix protein or loss of its functionality and structure. To preserve the natural microstructure, stabilizers or various modifications (slow/fast freezing, reducing the degree of supercooling, etc.) of the lyophilization process are applied to biological prostheses. In this review, the main processes of lyophilization of biological tissue are described, which can affect the operation of a cardiac implant. A deep understanding of the parameters of the lyophilization process is crucial for creation of stable tissue grafts and their subsequent long-term storage.

Shelf-Life Extension of Fc-Fused Single Chain Fragment Variable Antibodies by Lyophilization

Generation of sequence defined antibodies from universal libraries by phage display has been established over the past three decades as a robust method to cope with the increasing market demand in therapy, diagnostics and research. For applications requiring the bivalent antigen binding and an Fc part for detection, phage display generated single chain Fv (scFv) antibody fragments can rapidly be genetically fused to the Fc moiety of an IgG for the production in eukaryotic cells of antibodies with IgG-like properties. In contrast to conversion of scFv into IgG format, the conversion to scFv-Fc requires only a single cloning step, and provides significantly higher yields in transient cell culture production than IgG. ScFv-Fcs can be effective as neutralizing antibodies in vivo against a panel of pathogens and toxins. However, different scFv fragments are more heterologous in respect of stability than Fab fragments. While some scFv fragments can be made extremely stable, this may change due to few mutations, and is not predictable from the sequence of a newly selected antibody. To mitigate the necessity to assess the stability for every scFv-Fc antibody, we developed a generic lyophilization protocol to improve their shelf life. We compared long-term stability and binding activity of phage display-derived antibodies in the scFv-Fc and IgG format, either stored in liquid or lyophilized state. Conversion of scFv-Fcs into the full IgG format reduced protein degradation and aggregation, but in some cases compromised binding activity. Comparably to IgG conversion, lyophilization of scFv-Fc resulted in the preservation of the antibodies' initial properties after storage, without any drop in affinity for any of the tested antibody clones.

Cycle Development in a Mini-Freeze Dryer: Evaluation of Manometric Temperature Measurement in Small-Scale Equipment

The objective of this research was to assess the applicability of manometric temperature measurement (MTM) and SMART™ for cycle development and monitoring of critical product and process parameters in a mini-freeze dryer using a small set of seven vials. Freeze drying cycles were developed using SMART™ which automatically defines and adapts process parameters based on input data and MTM feedback information. The freeze drying behavior and product characteristics of an amorphous model system were studied at varying wall temperature control settings of the cylindrical wall surrounding the shelf in the mini-freeze dryer. Calculated product temperature profiles were similar for all different wall temperature settings during the MTM-SMART™ runs and in good agreement with the temperatures measured by thermocouples. Product resistance profiles showed uniformity in all of the runs conducted in the mini-freeze dryer, but absolute values were slightly lower compared to values determined by MTM in a LyoStar™ pilot-scale freeze dryer. The resulting cakes exhibited comparable residual moisture content and optical appearance to the products obtained in the larger freeze dryer. An increase in intra-vial heterogeneity was found for the pore morphology in the cycle with deactivated wall temperature control in the mini-freeze dryer. SMART™ cycle design and product attributes were reproducible and a minimum load of seven 10R vials was identified for more accurate MTM values. MTM-SMART™ runs suggested, that in case of the wall temperature following the product temperature of the center vial, product temperatures differ only slightly from those in the LyoStar™ freeze dryer.

Instability of therapeutic proteins - An overview of stresses, stabilization mechanisms and analytical techniques involved in lyophilized proteins

Solid-state is the preferred choice for storage of protein therapeutics to improve stability and preserve the biological activity by decreasing the physical and chemical degradation associated with liquid protein formulations. Lyophilization or freeze-drying is an effective drying method to overcome the instability problems of proteins. However, the processing steps (freezing, primary drying and secondary drying) involved in the lyophilization process can expose the proteins to various stress and harsh conditions, leading to denaturation, aggregation often a loss in activity of protein therapeutics. Stabilizers such as sugars and surfactants are often added to protect the proteins against physical stress associated with lyophilization process and storage conditions. Another way to curtail the degradation of proteins due to process related stress is by modification of the lyophilization process. Slow freezing, high nucleation temperature, decreasing the extent of supercooling, and annealing can minimize the formation of the interface (ice-water) by producing large ice crystals with less surface area, thereby preserving the native structure and stability of the proteins. Hence, a thorough understanding of formulation composition, lyophilization process parameters and the choice of analytical methods to characterize and monitor the protein instability is crucial for development of stable therapeutic protein products. This review provides an overview of various stress conditions that proteins might encounter during lyophilization process, mechanisms to improve the stability and analytical techniques to tackle the proteins instability during both freeze-drying and storage.

Lyophilization of Small-Molecule Injectables: an Industry Perspective on Formulation Development, Process Optimization, Scale-Up Challenges, and Drug Product Quality Attributes

Lyophilization is a pivotal manufacturing process to obtain a stable drug product that is unstable as a ready-to-use formulation. Some formulations may require the addition of drug-specific excipients such as stabilizers, buffers, and bulking agents to support the cake appearance and ensure long-term stability of the drug product. Optimization of the lyophilization process parameters at each stage including freezing and primary and secondary drying is important because these parameters can have a direct impact on the process efficiency (shortened cycle time) and product performance (cake appearance and homogeneous moisture content). Several parameters of the formulation, including properties of the active pharmaceutical ingredient, excipients, solvent system, and container closure, determine the success of lyophilization. Development, scale-up, and transfer of the lyophilization cycle are challenging; hence, a comprehensive understanding of the critical parameters related to the formulation, lyophilization process, and lyophilizer design allows designing a quality drug product. One approach for a successful transfer of the lyophilization cycle between the laboratory and commercial-scale lyophilizer is using vial heat transfer coefficient and ice slab test to establish a maximum sublimation rate. This review provides a general overview of the lyophilization process and discusses several key considerations and product development aspects of formulation, process optimization, container closure system, scale-up principles, and drug product quality attributes from the industrial viewpoint. Grapical abstract.

Long-term stability of insulin glulisine loaded nanoparticles formulated using an amphiphilic cyclodextrin and designed for intestinal delivery

Long-term stability is one of the main challenges for translation of therapeutic proteins into commercially viable biopharmaceutical products. During processing and storage, proteins are susceptible to denaturation. The aim of this work was to evaluate the stability of amphiphilic cyclodextrin-based nanoparticles (NPs) containing insulin glulisine. The stability of the NP dispersion was systematically evaluated following storage at three different temperatures (4 °C, room temperature (RT) and 40 °C). While the colloidal parameters of the NPs in terms of size and zeta potential were maintained (109 ± 9 nm, polydispersity index 0.272, negative zeta potential -25 ± 3 mV), insulin degraded over 60 days during storage. To enhance the shelf life of the product and to circumvent the need for cold-chain maintenance, a lyophilized formulation containing insulin glulisine NPs (1.75 mg/mL of NPs) and 25 mg/mL trehalose was produced. The freeze-dried powder extended the stability of the product for up to 30 days at ambient temperature and 90 days at 4 °C (with 95% and >80% insulin recovery, respectively). Following intra-intestinal administration of the freeze-dried formulation, while no lowering of blood glucose was seen, insulin glulisine was detected in both portal and systemic blood indicating that potential exists for further development of the formulation to simultaneously achieve prolonged stability and therapeutic efficacy.

Shelf-Life Evaluation and Lyophilization of PBCA-Based Polymeric Microbubbles

Poly(n-butyl cyanoacrylate) microbubbles (PBCA-MB) are extensively employed for functional and molecular ultrasound (US) imaging, as well as for US-mediated drug delivery. To facilitate the use of PBCA-MB as a commercial platform for biomedical applications, it is important to systematically study and improve their stability and shelf-life. In this context, lyophilization (freeze drying) is widely used to increase shelf-life and promote product development. Here, we set out to analyze the stability of standard and rhodamine-B loaded PBCA-MB at three different temperatures (4 °C, 25 °C, and 37 °C), for a period of time of up to 20 weeks. In addition, using sucrose, glucose, polyvinylpyrrolidone (PVP), and polyethylene glycol (PEG) as cryoprotectants, we investigated if PBCA-MB can be lyophilized without affecting their size, concentration, US signal generation properties, and dye retention. Stability assessment showed that PBCA-MB remain largely intact for three and four weeks at 4 °C and 25 °C, respectively, while they disintegrate within one to two weeks at 37 °C, thereby compromising their acoustic properties. Lyophilization analyses demonstrated that PBCA-MB can be efficiently freeze-dried with 5% sucrose and 5% PVP, without changing their size, concentration, and US signal generation properties. Experiments involving rhodamine-B loaded MB indicated that significant dye leakage from the polymeric shell takes place within two to four weeks in case of non-lyophilized PBCA-MB. Lyophilization of rhodamine-loaded PBCA-MB with sucrose and PVP showed that the presence of the dye does not affect the efficiency of freeze-drying, and that the dye is efficiently retained upon MB lyophilization. These findings contribute to the development of PBCA-MB as pharmaceutical products for preclinical and clinical applications.

Lyophilization of Synthetic Gene Carriers

Lyophilization, also known as freeze drying, is a widely used method for stabilization, improvement of long-term storage stability, and simplification of handling of drugs and/or carrier systems. Lyophilization is time-consuming and energy-consuming, and hence optimized processes are required to avoid time loss and higher costs without compromising product stability. Beginning from the last decade, nonviral, synthetic carriers for gene delivery have been of increasing interest. However, these systems suffer from poor physical stability in aqueous solution or suspension. Hence, to ensure long-term storage stability lyophilization of the gene carrier systems is favored. This chapter gives an overview of the basic steps and troubleshooting for successful lyophilization of synthetic gene carriers. Furthermore, the required excipients and their mechanism of action are summarized.

Exploring the chemical space for freeze-drying excipients

Commonly, a limited number of generally accepted bulking agents and lyoprotectants are used for freeze-drying; predominantly mannitol, glycine, sucrose and trehalose. The purpose of this study was to combine a theoretical approach using molecular descriptors with a large scale experimental screening to evaluate the suitability of a broad range of excipients for freeze-drying. A large selection of sugars, polyols and amino acids was characterized by modulated differential scanning calorimetry (mDSC) and X-ray powder diffraction (XRPD) after well-plate based freeze-drying. The calculated molecular descriptors were investigated with both hierarchical cluster analysis and principal component analysis. A clear clustering of the excipients according to the size-related and weight-related descriptors was observed; however other relevant descriptors could also be identified. From a practical perspective, a trend was observed with regard to a higher likelihood for amorphisation and a higher glass transition temperature of the maximally freeze-concentrated solution with increasing molecular size. A translation of the molecular descriptors on pharmaceutical performance was more successful for lyoprotectants than for bulking agents. Additionally, in the course of the experimental screening, several new potential bulking agents and lyoprotectants were identified.

Parenteral protein formulations: An overview of approved products within the European Union

The study presented is a comprehensive overview of commercial parenteral protein formulations, approved by the European Medicines Agency (EMA), 1995-2018. The objective of this overview was to analyse current trends in the design of commercial parenteral protein products and thereby support formulation scientists in the design of new formulations. The main data source was the publicly available European Public Assessment Reports (EPARs) published by the EMA for each authorised product. An analysis of the percentage of formulations in a liquid and lyophilised form was conducted. In addition, the number of products containing individual excipients, classified into functional categories is provided. Finally, the overview includes comprehensive details of product compositions obtained from EMA, US Food and Drug Administration (FDA) and product Marketing Authorisation Holder. Data analysis highlighted trends in the number of products approved, and the higher percentage of liquid parenteral protein formulations (66%) compared to lyophilised formulations (34%). This overview identifies the most commonly incorporated excipients employed as buffering agents, stabilisers/bulking agents, surfactants, preservatives and tonicifiers, including their concentration ranges of use in both liquid and lyophilised formulation approaches. Finally, antibody-based formulations were a particular focus of this overview. The relationship between parenteral routes of administration and antibody concentrations in approved products was also investigated.

The Chemistry of Lyophilized Blood Products

With the development of new biologics and bioconjugates, storage and preservation have become more critical than ever before. Lyophilization is a method of cell and protein preservation by removing a solvent such as water from a substance followed by freezing. This technique has been used in the past and still holds promise for overcoming logistic challenges in safety net hospitals with limited blood banking resources, austere environments such as combat, and mass casualty situations where existing resources may be outstripped. This method allows for long-term storage and transport but requires the bioconjugation of preservatives to prevent cell destabilization. Trehalose is utilized as a bioconjugate in platelet and red blood cell preservation to maintain protein thermodynamics and stabilizing protein formulations in liquid and freeze-dried states. Biomimetic approaches have been explored as alternatives to cryo- and lyopreservation of blood components. Intravascular hemostats such as PLGA nanoparticles functionalized with PEG motifs, topical hemostats utilizing fibrinogen or chitosan, and liposomal encapsulated hemoglobin with surface modifications are effectively stored long-term through bioconjugation. In thinking about the best methods for storage and transport, we are focusing this topical review on blood products that have the longest track record of preservation and looking at how these methods can be applied to synthetic systems.

Finite Element Method (FEM) Modeling of Freeze-drying: Monitoring Pharmaceutical Product Robustness During Lyophilization

Lyophilization is an approach commonly undertaken to formulate drugs that are unstable to be commercialized as ready to use (RTU) solutions. One of the important aspects of commercializing a lyophilized product is to transfer the process parameters that are developed in lab scale lyophilizer to commercial scale without a loss in product quality. This process is often accomplished by costly engineering runs or through an iterative process at the commercial scale. Here, we are highlighting a combination of computational and experimental approach to predict commercial process parameters for the primary drying phase of lyophilization. Heat and mass transfer coefficients are determined experimentally either by manometric temperature measurement (MTM) or sublimation tests and used as inputs for the finite element model (FEM)-based software called PASSAGE, which computes various primary drying parameters such as primary drying time and product temperature. The heat and mass transfer coefficients will vary at different lyophilization scales; hence, we present an approach to use appropriate factors while scaling-up from lab scale to commercial scale. As a result, one can predict commercial scale primary drying time based on these parameters. Additionally, the model-based approach presented in this study provides a process to monitor pharmaceutical product robustness and accidental process deviations during Lyophilization to support commercial supply chain continuity. The approach presented here provides a robust lyophilization scale-up strategy; and because of the simple and minimalistic approach, it will also be less capital intensive path with minimal use of expensive drug substance/active material.

Nanoparticulate Impurities in Pharmaceutical-Grade Sugars and their Interference with Light Scattering-Based Analysis of Protein Formulations

PURPOSE

In the present study we investigated the root-cause of an interference signal (100-200 nm) of sugar-containing solutions in dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA) and its consequences for the analysis of particles in biopharmaceutical drug products.

METHODS

Different sugars as well as sucrose of various purity grades, suppliers and lots were analyzed by DLS and NTA before and (only for sucrose) after treatment by ultrafiltration and diafiltration. Furthermore, Fourier transform infrared (FTIR) microscopy, scanning electron microscopy coupled energy-dispersive X-ray spectroscopy (SEM-EDX), and fluorescence spectroscopy were employed.

RESULTS

The intensity of the interference signal differed between sugar types, sucrose of various purity grades, suppliers, and batches of the same supplier. The interference signal could be successfully eliminated from a sucrose solution by ultrafiltration (0.02 μm pore size). Nanoparticles, apparently composed of dextrans, ash components and aromatic colorants that were not completely removed during the sugar refinement process, were found responsible for the interference and were successfully purified from sucrose solutions.

CONCLUSIONS

The interference signal of sugar-containing solutions in DLS and NTA is due to the presence of nanoparticulate impurities. The nanoparticles present in sucrose were identified as agglomerates of various impurities originating from raw materials.

Freeze-drying of plant tissue containing HBV surface antigen for the oral vaccine against hepatitis B

The aim of this study was to develop a freeze-drying protocol facilitating successful processing of plant material containing the small surface antigen of hepatitis B virus (S-HBsAg) while preserving its VLP structure and immunogenicity. Freeze-drying of the antigen in lettuce leaf tissue, without any isolation or purification step, was investigated. Each process step was consecutively evaluated and the best parameters were applied. Several drying profiles and excipients were tested. The profile of 20°C for 20 h for primary and 22°C for 2 h for secondary drying as well as sucrose expressed efficient stabilisation of S-HBsAg during freeze-drying. Freezing rate and postprocess residual moisture were also analysed as important factors affecting S-HBsAg preservation. The process was reproducible and provided a product with VLP content up to 200 µg/g DW. Assays for VLPs and total antigen together with animal immunisation trials confirmed preservation of antigenicity and immunogenicity of S-HBsAg in freeze-dried powder. Long-term stability tests revealed that the stored freeze-dried product was stable at 4°C for one year, but degraded at elevated temperatures. As a result, a basis for an efficient freeze-drying process has been established and a suitable semiproduct for oral plant-derived vaccine against HBV was obtained.

Differential effect of buffering agents on the crystallization of gemcitabine hydrochloride in frozen solutions

The purpose of this study was to evaluate the differential effect of buffering agents on the crystallization of gemcitabine hydrochloride (GHCl) in frozen solutions. Four buffering agents, viz. citric acid (CA), malic acid (MA), succinic acid (SA) and tartaric acid (TA) were selected and their effect on GHCl crystallization was monitored using standard DSC and low temperature XRD. Onset of GHCl crystallization during heating run in DSC was measured to compare the differential effect of buffering agents. Glass transition temperature (Tg'), unfrozen water content in the freeze concentrate and crystallization propensity of the buffering agents was also determined for mechanistic understanding of the underlying effects. CA and MA inhibited while SA facilitated crystallization of GHCl even at 25 mM concentration. Increasing the concentration enhanced their effect. However, TA inhibited GHCl crystallization at concentrations <100mM and facilitated it at concentrations ≥100 mM. Lyophilization of GHCl with either SA or TA yielded elegant cakes, while CA and MA caused collapse. Tg' failed to explain the inhibitory effects of CA, MA and TA as all buffering agents lowered the Tg' of the system. Differential effect of buffering agents on GHCl crystallization could be explained by consideration of two opposing factors: (i) their own crystallization tendency and (ii) unfrozen water content in the freeze concentrate. In conclusion, it was established that API crystallization in frozen solution is affected by the type and concentration of the buffering agents.

Lyophilization of synthetic gene carriers

Lyophilization, also known as freeze-drying, is a widely used method for stabilization, improvement of long-term storage stability, and simplification of the handling of drugs and/or carrier systems. Lyophilization is time- and energy-consuming; hence, optimized processes are required to avoid time loss and higher costs without compromising product stability. Since the last decade nonviral, synthetic carriers for gene delivery are of increasing interest. However, these systems suffer from poor physical stability in aqueous solution or suspension. Hence, to ensure long-term storage stability lyophilization of the gene carrier systems is favored. Though, lyophilized products retrieving original carrier size and transfection efficiency after reconstitution are mandatory. This chapter gives an overview of the basic steps and troubleshooting for successful lyophilization of synthetic gene carriers. Furthermore the required excipients and their mechanism of action are summarized.

Characterizing the freeze-drying behavior of model protein formulations

The freeze-drying behavior of three model proteins, namely, lysozyme, BSA, and IgG, has been studied using a variety of techniques under two different primary drying conditions (shelf temperatures of -25°C and +25°C, respectively) in an amorphous formulation. Manometric temperature measurements were used to characterize product temperature (T (pr)), sublimation rates, and product resistance (R (p)) during primary drying. Biophysical techniques such as circular dichroism, fluorescence, and Fourier transform infrared spectroscopy were used to study protein conformation. Size exclusion chromatography was used to monitor the formation of high-molecular-weight species (HMWS) over time on storage, and cake morphology was studied using scanning electron microscopy. The differences in the freeze-drying behavior of the three proteins were more evident at higher protein concentrations, where the protein significantly influences the behavior of the formulation matrix. However, these differences were minimized in the aggressive mode and were insignificant at lower protein concentrations where excipients dominated the freeze-drying behavior. Differences in cake morphology were observed between the two drying conditions employed as well as between the three proteins studied. The stability and the protein structure, however, were equivalent for the protein cakes generated using the two different primary drying conditions.

Non-invasive product temperature determination during primary drying using tunable diode laser absorption spectroscopy

The goal of this work was to demonstrate the application of Tunable Diode Laser Absorption Spectroscopy (TDLAS) as a non-invasive method to determine the average product temperature of the batch during primary drying. The TDLAS sensor continuously measures the water vapor concentration and the vapor flow velocity in the spool connecting the freeze-dryer chamber and condenser. Vapor concentration and velocity data were then used to determine the average sublimation rate (g/s) which was subsequently integrated to evaluate the amount of water removed from the product. Position dependent vial heat transfer coefficients (K(v)) were evaluated using the TDLAS sensor data for 20 mL vials during sublimation tests with pure water. TDLAS K(v) data showed good agreement to K(v) data obtained by the traditional gravimetric procedure. K(v) for edge vials was found to be about 20-30% higher than that of center vials. A weighted K(v) was then used to predict a representative average product temperature from TDLAS data in partial and full load freeze drying runs with 5%, 7.5%, or 10% (w/w) sucrose, mannitol, and glycine solutions. TDLAS product temperatures for all freeze-drying runs were within 1-2 degrees C of "center vial" steady state thermocouple data.

Freeze-dry microscopy: impact of nucleation temperature and excipient concentration on collapse temperature data

The objective of this study was to investigate the impact of nucleation temperature (T(n)) and excipient concentration on the collapse temperature data obtained from freeze-dry microscopy (FDM) experiments. T(n), the temperature of the onset of collapse (T(oc)), and the full collapse temperature (T(fc)) were determined for aqueous solutions of polyvinylpyrrolidone (PVP) 40 kDa and 2-(hydroxypropyl)-beta-cyclodextrin. Concentrations were varied from 1% to 20% (w/w) for PVP and from 1% to 30% (w/w) for the 2-(hydroxypropyl)-beta-cyclodextrin. Mutual correlation coefficients were calculated for the observed T(n), T(oc), and concentrations of the solutions. In addition, outliers were detected and eliminated by applying the leaving-one-out routine and calculating correlation coefficients without it. T(n) was found to be non-correlated with concentrations and only weakly correlated with T(oc). The correlation between these two temperatures was particularly poor for the solutions of the highest and lowest concentrations. In contrast, T(oc) correlated much better with the corresponding concentrations, resulting in a quadratic fit for PVP and a linear fit for 2-(hydroxypropyl)-beta-cyclodextrin.

Proton-detected solid-state NMR spectroscopy of natural-abundance peptide and protein pharmaceuticals

The natural way: A sensitive NMR spectroscopic method is developed to obtain well-resolved two-dimensional spectra ((15)N-(1)H and (13)C-(1)H) for natural-abundance (that is, without the need for isotopic enrichment) large-molecule samples, such as biopharmaceuticals. This method gives structural insights on two lyophilized aprotinin samples and three insulin samples in lyophilized, microcrystalline suspension formulation (red; see picture) and fibril (green) forms.