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

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.

Trehalose-conjugated lentil-casein protein complexes prepared by structural interaction: Effects on water solubility and protein digestibility

The two limiting factors for lentil protein utilization are water solubility and digestibility. In this study, we utilized two non-thermal techniques: (1) protein complexation of lentil and casein proteins using the pH-shifting method and (2) protein conjugation with trehalose to produce trehalose-conjugated lentil-casein protein complexes (T-CPs) with enhanced water solubility and digestibility. The protein structure of the T-CPs was analyzed for secondary protein structure, conformation protein, and tertiary protein structure using Fourier-transform infrared, UV, and fluorescence spectroscopies, respectively. The surface hydrophobicity and surface charge of T-CPs solution at pH 7.0 changed significantly (P < 0.05). Using these two non-thermal techniques, the water solubility and digestibility of T-CPs increased significantly (P < 0.05) by 85 to 89 % and 80 to 85 %, respectively. The results of this study suggested that these non-thermal techniques could enhance the surface and protein structure properties, improving water solubility and digestibility.

Evaluation of digestibility, solubility, and surface properties of trehalose-conjugated quinoa proteins prepared via pH shifting technique

Soluble trehalose-conjugated quinoa proteins (T-QPs) were effectively prepared using the pH-shifting mechanism. The structural properties of the T-QPs were evaluated using a comparative evaluation, which included analyzing the amide I, surface charge and hydrophobicity, protein conformation, thermal stability, and protein structures. The results suggested that the development of the T-QPs was influenced mainly by no-covalent bonds. These interactions significantly influenced (P < 0.05) the quinoa proteins' conformation and higher-protein structure. T-QP had significant (P < 0.05) surface properties. Furthermore, the T-QPs exhibited improved solubility (79.7 to 88.4%) and digestibility (79.8 to 85.1%). Therefore, quinoa protein proved an excellent plant-based protein for conjugation with disaccharides. These findings provide significant insight into the potential development of modified proteins with enhanced solubility and digestibility by creating trehalose-conjugated plant-based proteins.

Homogeneous heat transfer during freeze-drying using cyclic olefin polymer vials

In pharmaceutical freeze-drying processes, batch homogeneity is an important quality attribute. In this context, the edge-vial-effect is a challenging phenomenon. Shortly, this effect describes that vials at the edges of the shelf dry faster and at a higher temperature compared to vials in the middle of the shelf. Studies by Ehlers et al. revealed that this effect mainly origins from the number of neighbor vials cooling each other, which is reduced for vials in corners and edges compared to vials in the middle. Due to the reduced heat transfer in cyclic olefin polymer (COP) vials, the adverse edge-vial-effect should be greatly reduced allowing a better batch uniformity. In this focused study, glass and COP vials are compared regarding this effect on a fully loaded shelf. A reference experiment with vials placed at distance using a specially designed frame is presented as well.

Neutrophil-derived nanovesicles deliver IL-37 to mitigate renal ischemia-reperfusion injury via endothelial cell targeting

Renal ischemia-reperfusion injury (IRI) is one of the most important causes of acute kidney injury (AKI). Interleukin (IL)-37 has been suggested as a novel anti-inflammatory factor for the treatment of IRI, but its application is still limited by its low stability and delivery efficiency. In this study, we reported a novel engineered method to efficiently and easily prepare neutrophil membrane-derived vesicles (N-MVs), which could be utilized as a promising vehicle to deliver IL-37 and avoid the potential side effects of neutrophil-derived natural extracellular vesicles. N-MVs could enhance the stability of IL-37 and targetedly deliver IL-37 to damaged endothelial cells of IRI kidneys via P-selectin glycoprotein ligand-1 (PSGL-1). In vitro and in vivo evidence revealed that N-MVs encapsulated with IL-37 (N-MV@IL-37) could inhibit endothelial cell apoptosis, promote endothelial cell proliferation and angiogenesis, and decrease inflammatory factor production and leukocyte infiltration, thereby ameliorating renal IRI. Our study establishes a promising delivery vehicle for the treatment of renal IRI and other endothelial damage-related diseases.

Improved Protein Removal Performance of PES Hollow-Fiber Ultrafiltration Membrane with Sponge-like Structure

The research used polyethersulfone (PES) as a membrane material, polyvinylpyrrolidone (PVP) k30 and polyethylene glycol 400 (PEG 400) as water-soluble additives, and dimethylacetamide (DMAc) as a solvent to prepare hollow-fiber ultrafiltration membranes through a nonsolvent-induced phase separation (NIPS) process. The hydrophilic nature of PVP-k30 and PEG caused them to accumulate on the membrane surface during phase separation. The morphology, chemical composition, surface charge, and pore size of the PES membranes were evaluated by SEM, FTIR, zeta potential, and dextran filtration experiments. The paper also investigated how different spinning solution compositions affected membrane morphology and performance. The separation efficiency of membranes with four different morphologies was tested in single-protein and double-protein mixed solutions. The protein separation effectiveness of the membrane was studied through molecular weight cutoff, zeta potential, and static protein adsorption tests. In addition, the operating pressure and pH value were adjusted to improve ultrafiltration process conditions. The PES membrane with an intact sponge-like structure showed the highest separation factor of 11, making it a prime candidate membrane for the separation of bovine serum albumin (BSA) and lysozyme (LYS). The membrane had a minimal static protein adsorption capacity of 48 mg/cm2 and had excellent anti-fouling properties. When pH = 4, the BSA retention rate was 93% and the LYS retention rate was 23%. Furthermore, it exhibited excellent stability over a pH range of 1-13, confirming its suitability for protein separation applications.

Recent advancements in the specific determination of carcinoembryonic antigens using MOF-based immunosensors

Carcinoembryonic antigens (CEAs) are prominent cancer biomarkers that enable the early detection of numerous cancers. For effective CEA screening, rapid, portable, efficient, and sensitive diagnosis approaches should be devised. Metal-organic frameworks (MOFs) are porous crystalline materials that have received major attention for application in high-efficiency signal probes owing to their advantages such as large specific surface area, superior chemical stability and tunability, high porosity, easy surface functional modification, and adjustable size and morphology. Immunoassay strategies using antigen-antibody specific interaction are one of the imperative means for rapid and accurate measurement of target molecules in biochemical fields. The emerging MOFs and their nanocomposites are synthesized with excellent features, providing promising potential for immunoassays. This article outlines the recent breakthroughs in the synthesis approaches of MOFs and overall functionalization mechanisms of MOFs with antigen/antibody and their uses in the CEA immunoassays, which operate according to electrochemical, electrochemiluminescent and colorimetric techniques. The prospects and limitations of the preparation and immunoassay applications of MOF-derived hybrid nanocomposites are also discussed at the end.

Effects of freezing and drying programs on IgY aggregation and activity during microwave freeze-drying: Protective effects and interactions of trehalose and mannitol

The acquisition of high quality lyophilized IgY products, characterized by an aesthetically pleasing visage, heightened stability, and a marked preservation of activity, constitutes an indispensable pursuit in augmenting the safety and pragmatic utility of IgY. Within this context, an exploration was undertaken to investigate an innovative modality encompassing microwave freeze-drying (MFD) as a preparatory methodology of IgY. Morphological assessments revealed that both cryogenic freezing and subsequent MFD procedures resulted in aggregation of IgY, with the deleterious influence posed by the MFD phase transcending that of the freezing phase. The composite protective agent comprised of trehalose and mannitol engendered a safeguarding effect on the structural integrity of IgY, thereby attenuating reducing aggregation between IgY during the freeze-drying process. Enzyme-linked immunosorbent assay (ELISA) outcomes demonstrated a discernible correlation between IgY aggregation and a notable reduction in its binding affinity towards the pertinent antigen. Comparative analysis vis-à-vis the control sample delineated that when the trehalose-to-mannitol ratio was upheld at 1:3, a two-fold outcome was achieved: a mitigation of the collapse susceptibility within the final product as well as a deterrence of IgY agglomeration, concomitant with an elevated preservation rate of active antibodies (78.57 %).

Ionic liquids and deep eutectic solvents for the stabilization of biopharmaceuticals: A review

Biopharmaceuticals have allowed the control of previously untreatable diseases. However, their low solubility and stability still hinder their application, transport, and storage. Hence, researchers have applied different compounds to preserve and enhance the delivery of biopharmaceuticals, such as ionic liquids (ILs) and deep eutectic solvents (DESs). Although the biopharmaceutical industry can employ various substances for enhancing formulations, their effect will change depending on the properties of the target biomolecule and environmental conditions. Hence, this review organized the current state-of-the-art on the application of ILs and DESs to stabilize biopharmaceuticals, considering the properties of the biomolecules, ILs, and DESs classes, concentration range, types of stability, and effect. We also provided a critical discussion regarding the potential utilization of ILs and DESs in pharmaceutical formulations, considering the restrictions in this field, as well as the advantages and drawbacks of these substances for medical applications. Overall, the most applied IL and DES classes for stabilizing biopharmaceuticals were cholinium-, imidazolium-, and ammonium-based, with cholinium ILs also employed to improve their delivery. Interestingly, dilute and concentrated ILs and DESs solutions presented similar results regarding the stabilization of biopharmaceuticals. With additional investigation, ILs and DESs have the potential to overcome current challenges in biopharmaceutical formulation.

Alu'datt M, R. Al Qudsi F, Tan TC, A. Razzak Mahmood A, Maghaydah S. Molecular forces driving protein complexation of lentil and whey proteins: Structure-function relationships of trehalose-conjugated protein complexes on protein digestibility and solubility

Plant-based proteins are often associated with a range of health benefits. Most research primarily investigates pea and soy proteins, while lentil proteins received minimal attention. This study evaluates the effect of protein complexation (using the pH-shifting technique) coupled with trehalose conjugation on lentil and whey proteins. The protein structures after the modification were analysed using spectroscopic methods: Fourier-transform infrared, ultraviolet spectra, and fluorescence spectra. The amide group I, conformation protein, and tertiary structure of the trehalose-conjugated lentil-whey protein complexes (T-LWPs) showed significant changes (P < 0.05). Moreover, the surface properties (surface hydrophobicity and charges) of T-LWPs were significantly modified (P < 0.05), from 457 to 324 a.u and from 36 to -40 mV, respectively. Due to these modifications on the protein structures, the protein digestibility (80-86%) and water solubility (90-94.5%) of T-LWPs increased significantly (P < 0.05) with the increase in the trehalose concentration, from 0 (control) to 5% (w/w), respectively. This study suggested that coupling protein complexation and trehalose conjugation can enhance the overall properties of lentil-based protein complexes. With this enhancement, more opportunities in the utilisation of lentils are to be expected.

The Effects of Excipients on Freeze-dried Monoclonal Antibody Formulation Degradation and Sub-Visible Particle Formation during Shaking

PURPOSES

We previously reported an unexpected phenomenon that shaking stress could cause more protein degradation in freeze-dried monoclonal antibody (mAb) formulations than liquid ones (J Pharm Sci, 2022, 2134). The main purposes of the present study were to investigate the effects of shaking stress on protein degradation and sub-visible particle (SbVP) formation in freeze-dried mAb formulations, and to analyze the factors influencing protein degradation during production and transportation.

METHODS

The aggregation behavior of mAb-X formulations during production and transportation was simulated by shaking at a rate of 300 rpm at 25°C for 24 h. The contents of particles and monomers were analyzed by micro-flow imaging, dynamic light scattering, size exclusion chromatography, and ultraviolet - visible (UV-Vis) spectroscopy to compare the protective effects of excipients on the aggregation of mAb-X.

RESULTS

Shaking stress could cause protein degradation in freeze-dried mAb-X formulations, while surfactant, appropriate pH, polyol mannitol, and high protein concentration could impact SbVP generation. Water content had little effect on freeze-dried protein degradation during shaking, as far as the water content was controlled in the acceptable range as recommended by mainstream pharmacopoeias (i.e., less than 3%).

CONCLUSIONS

Shaking stress can reduce the physical stability of freeze-dried mAb formulations, and the addition of surfactants, polyol mannitol, and a high protein concentration have protective effects against the degradation of model mAb formulations induced by shaking stress. The experimental results provide new insight for the development of freeze-dried mAb formulations.

Design of functional intrinsically disordered proteins

Many proteins do not fold into a fixed three-dimensional structure, but rather function in a highly disordered state. These intrinsically disordered proteins pose a unique challenge to protein engineering and design: How can proteins be designed de novo if not by tailoring their structure? Here, we will review the nascent field of design of intrinsically disordered proteins with focus on applications in biotechnology and medicine. The design goals should not necessarily be the same as for de novo design of folded proteins as disordered proteins have unique functional strengths and limitations. We focus on functions where intrinsically disordered proteins are uniquely suited including disordered linkers, desiccation chaperones, sensors of the chemical environment, delivery of pharmaceuticals, and constituents of biomolecular condensates. Design of functional intrinsically disordered proteins relies on a combination of computational tools and heuristics gleaned from sequence-function studies. There are few cases where intrinsically disordered proteins have made it into industrial applications. However, we argue that disordered proteins can perform many roles currently performed by organic polymers, and that these proteins might be more designable due to their modularity.

Shear stress as a driver of degradation for protein-based therapeutics: More accomplice than culprit

Protein degradation is a major concern for protein-based therapeutics. It may alter the biological activity of the product and raise the potential for undesirable effects on the patients. Among the numerous drivers of protein degradation, shear stress has been the focus around which much work has revolved since the 1970s. In the pharmaceutical realm, the product is often processed through several unit operations, which include mixing, pumping, filtration, filling, and atomization. Nonetheless, the drug might be exposed to significant shear stresses, which might cooperatively contribute to product degradation, together with interfacial stress. This review presents fundamentals of shear stress about protein structure, followed by an overview of the drivers of product degradation. The impact of shear stress on protein stability in different unit operations is then presented, and recommendations for limiting the adverse effects on the biopharmaceutical formulations are outlined. Finally, several devices used to explore the effects of shear stress are discussed.

Optimizing Excipient Properties to Prevent Aggregation in Biopharmaceutical Formulations

Excipients are included within protein biotherapeutic solution formulations to improve colloidal and conformational stability but are generally not designed for the specific purpose of preventing aggregation and improving cryoprotection in solution. In this work, we have explored the relationship between the structure and antiaggregation activity of excipients by utilizing coarse-grained molecular dynamics modeling of protein-excipient interaction. We have studied human serum albumin as a model protein, and we report the interaction of 41 excipients (polysorbates, fatty alcohol ethoxylates, fatty acid ethoxylates, phospholipids, glucosides, amino acids, and others) in terms of the reduction of solvent accessible surface area of aggregation-prone regions, proposed as a mechanism of aggregation prevention. Polyoxyethylene sorbitan had the greatest degree of interaction with aggregation-prone regions, decreasing the solvent accessible surface area of APRs by 20.7 nm2 (40.1%). Physicochemical descriptors generated by Mordred are employed to probe the structure-property relationship using partial least-squares regression. A leave-one-out cross-validated model had a root-mean-square error of prediction of 4.1 nm2 and a mean relative error of prediction of 0.077. Generally, longer molecules with a large number of alcohol-terminated PEG units tended to interact more, with qualitatively different protein interactions, wrapping around the protein. Shorter or less ethoxylated compounds tend to form hemimicellar clusters at the protein surface. We propose that an improved design would feature many short chains of 5 to 10 PEG units in many distinct branches and at least some hydrophobic content in the form of medium-length or greater aliphatic chains (i.e., six or more carbon atoms). The combination of molecular dynamics simulation and quantitative modeling is an important first step in an all-purpose protein-independent model for the computer-aided design of stabilizing excipients.

Influence of water and trehalose on α- and β-relaxation of freeze-dried lysozyme formulations

Molecular mobility in form of alpha and beta relaxations is considered crucial for characterization of amorphous lyophilizates and reflected in the transition temperatures Tgα and Tgβ. Based on an overview of applied methods to study beta relaxations, Dynamic Mechanical analysis was used to measure Tgα and Tgβ in amorphous freeze-dried samples. Lysozyme and trehalose as well as their mixtures in varying ratios were investigated. Three different residual moisture levels, ranging from roughly 0.5-7 % (w/w), were prepared via equilibration of the freeze-dried samples. Known plasticising effects of water on Tgα were confirmed, also via differential scanning calorimetry. In addition and contrary to expectations, an influence of water on the Tgβ also was observed. On the other hand, an increasing amount of trehalose lowered Tgα but increased Tgβ showing that Tgα and Tgβ are not paired. The findings were interpreted with regard to their underlying molecular mechanisms and a correlation with the known influences of water and trehalose on stability. The results provide encouraging hints for future stability studies of freeze-dried protein formulations, which are urgently needed, not least for reasons of sustainability.

Stabilization effects of saccharides in protein formulations: A review of sucrose, trehalose, cyclodextrins and dextrans

Saccharides are a popular group of stabilizers in liquid, frozen and freeze dried protein formulations. The current work reviewed the stabilization mechanisms of three groups of saccharides: (i) Disaccharides, specifically sucrose and trehalose; (ii) cyclodextrins (CDs), a class of cyclic oligosaccharides; and (iii) dextrans, a class of polysaccharides. Compared to sucrose, trehalose exhibits a more pronounced preferential exclusion effect in liquid protein formulations, due to its stronger interaction with water molecules. However, trehalose obtains higher phase separation and crystallization propensity in frozen solutions, resulting in the loss of its stabilization function. In lyophilized formulations, sucrose has a higher crystallization propensity. Besides, its glass matrix is less homogeneous than that of trehalose, thus undermining its lyoprotectant function. Nevertheless, the hygroscopic nature of trehalose may result in high water absorption upon storage. Among all the CDs, the β form is believed to have stronger interactions with proteins than the α- and γ-CDs. However, the stabilization effect, brought about by CD-protein interactions, is case-by-case - in some examples, such interactions can promote protein destabilization. The stabilization effect of hydroxypropyl-β-cyclodextrin (HPβCD) has been extensively studied. Due to its amphiphilic nature, it can act as a surface-active agent in preventing interfacial stresses. Besides, it is a dual functional excipient in freeze dried formulations, acting as an amorphous bulking agent and lyoprotectant. Finally, dextrans, when combined with sucrose or trehalose, can be used to produce stable freeze dried protein formulations. A strong stabilization effect can be realized by low molecular weight dextrans. However, the terminal glucose in dextrans yields protein glycation, which warrants extra caution during formulation development.

Exploring the diverse applications of Carbohydrate macromolecules in food, pharmaceutical, and environmental technologies

Carbohydrates are a class of macromolecules that has significant potential across several domains, including the organisation of genetic material, provision of structural support, and facilitation of defence mechanisms against invasion. Their molecular diversity enables a vast array of essential functions, such as energy storage, immunological signalling, and the modification of food texture and consistency. Due to their rheological characteristics, solubility, sweetness, hygroscopicity, ability to prevent crystallization, flavour encapsulation, and coating capabilities, carbohydrates are useful in food products. Carbohydrates hold potential for the future of therapeutic development due to their important role in sustained drug release, drug targeting, immune antigens, and adjuvants. Bio-based packaging provides an emerging phase of materials that offer biodegradability and biocompatibility, serving as a substitute for traditional non-biodegradable polymers used as coatings on paper. Blending polyhydroxyalkanoates (PHA) with carbohydrate biopolymers, such as starch, cellulose, polylactic acid, etc., reduces the undesirable qualities of PHA, such as crystallinity and brittleness, and enhances the PHA's properties in addition to minimizing manufacturing costs. Carbohydrate-based biopolymeric nanoparticles are a viable and cost-effective way to boost agricultural yields, which is crucial for the increasing global population. The use of biopolymeric nanoparticles derived from carbohydrates is a potential and economically viable approach to enhance the quality and quantity of agricultural harvests, which is of utmost importance given the developing global population. The carbohydrate biopolymers may play in plant protection against pathogenic fungi by inhibiting spore germination and mycelial growth, may act as effective elicitors inducing the plant immune system to cope with pathogens. Furthermore, they can be utilised as carriers in controlled-release formulations of agrochemicals or other active ingredients, offering an alternative approach to conventional fungicides. It is expected that this review provides an extensive summary of the application of carbohydrates in the realms of food, pharmaceuticals, and environment.

Tableting properties of freeze-dried trehalose: Physico-chemical and mechanical investigation

Freeze-drying of biopharmaceutical products is the method of choice in order to improve their stability and storage conditions. Such freeze-dried products are usually intended for parenteral route administration. However, many biopharmaceutical materials administered by parenteral route are used to treat local diseases particularly in the gastro-intestinal tract. Therefore, many studies concentrate nowadays their effort on developing alternative dosage forms to deliver biopharmaceutical molecules by the oral route. Tablets are the most popular solid pharmaceutical dosage form used for oral administration since they present many advantages, but poor informations are available on the possibility of tableting freeze-dried powders. In this study, we evaluate the compaction behavior of freeze-dried trehalose powder since trehalose is one of the most used cryo and lyoprotectant for the lyophilisation of biopharmaceutical entities. Results show that freeze-dried trehalose powder can be tableted while remaining amorphous and the obtained compacts present very specific properties in terms of compressibility, tabletability, brittleness and viscoelasticity compared to the crystalline trehalose and compared to classical pharmaceutical excipients.

Solid-State NMR Spectroscopy to Probe State and Phase Transitions in Frozen Solutions

Freezing is commonly encountered during the processing and storage of biomacromolecule products. Therefore, understanding the phase and state transitions in pharmaceutical frozen solutions is crucial for the rational development of biopharmaceuticals. Solid-state nuclear magnetic resonance spectroscopy (ssNMR) was used to analyze solutions containing sodium phosphate buffer, histidine, and trehalose. Upon freezing, crystallization of disodium phosphate hydrogen dodecahydrate (Na2HPO4·12H2O, DPDH) and histidine was identified using 31P and 13C ssNMR, respectively, and confirmed by synchrotron X-ray diffractometry (SXRD). Using histidine as a molecular probe and based on the chemical shifts of atoms of interest, the pH of the freeze concentrate was measured. The unfrozen water content in freeze concentrates was quantified by 1H single pulse experiments. 13C-insensitive nuclei enhancement by polarization transfer (INEPT) and cross-polarization (CP) experiments were used as orthogonal tools to characterize the solutes in a "mobile" and a more "solid-like" state in the freeze-concentrated solutions, respectively. The above analyses were applied to a commercial monoclonal antibody (mAb) formulation of dupilumab. This work further establishes ssNMR spectroscopy as a highly capable biophysical tool to investigate the attributes of biopharmaceuticals and thereby provide insights into process optimization and formulation development.

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.

Solidification and oral delivery of biologics to the colon- A review

The oral delivery of biologics such as therapeutic proteins, peptides and oligonucleotides for the treatment of colon related diseases has been the focus of increasing attention over the last years. However, the major disadvantage of these macromolecules is their degradation propensity in liquid state which can lead to the undesirable and complete loss of function. Therefore, to increase the stability of the biologic and reduce their degradation propensity, formulation techniques such as solidification can be performed to obtain a stable solid dosage form for oral administration. Due to their fragility, stress exerted on the biologic during solidification has to be reduced with the incorporation of stabilizing excipients into the formulation. This review focuses on the state-of-the-art solidification techniques required to obtain a solid dosage form for the oral delivery of biologics to the colon and the use of suitable excipients for adequate stabilization upon solidification. The solidifying processes discussed within this review are spray drying, freeze drying, bead coating and also other techniques such as spray freeze drying, electro spraying, vacuum- and supercritical fluid drying. Further, the colon as site of absorption in both healthy and diseased state is critically reviewed and possible oral delivery systems for biologics are discussed.

Systematic review and meta-analysis of human health-related protein markers for realizing real-time wastewater-based epidemiology

For effective implementation of the wastewater-based epidemiology (WBE) approach, real-time quantification of markers in wastewater is critical for data acquisition before data interpretation, dissemination, and decision-making. This can be achieved by using biosensor technology, but whether the quantification/detection limits of different types of biosensors comply with the concentration of WBE markers in wastewater is unclear. In the present study, we identified promising protein markers with relatively high concentrations in wastewater samples and analyzed biosensor technologies that are potentially available for real-time WBE. The concentrations of potential protein markers in stool and urine samples were obtained through systematic review and meta-analysis. We examined 231 peer-review papers to collect information regarding potential protein markers that can enable us to achieve real-time monitoring using biosensor technology. Fourteen markers in stool samples were identified at the ng/g level, presumably equivalent to ng/L of wastewater after dilution. Moreover, relatively high average concentrations of fecal inflammatory proteins were observed, e.g., fecal calprotectin, clusterin, and lactoferrin. Fecal calprotectin exhibited the highest average log concentration among the markers identified in stool samples with its mean value being 5.24 [95 % CI: 5.05, 5.42] ng/g. We identified 50 protein markers in urine samples at the ng/mL level. Uromodulin (4.48 [95 % CI: 4.20, 4.76] ng/mL) and plasmin (4.18 [95 % CI: 3.15, 5.21] ng/mL) had the top two highest log concentrations in urine samples. Furthermore, the quantification limit of some electrochemical- and optical-based biosensors was found to be around the femtogram/mL level, which is sufficiently low to detect protein markers in wastewater even after dilution in sewer pipes.

From cell factories to patients: Stability challenges in biopharmaceuticals manufacturing and administration with mitigation strategies

Active ingredients of biopharmaceuticals consist of a wide array of biomolecular structures, including those of enzymes, monoclonal antibodies, nucleic acids, and recombinant proteins. Recently, these molecules have dominated the pharmaceutical industry owing to their safety and efficacy. However, their manufacturing is hindered by high cost, inadequate batch-to-batch equivalence, inherent instability, and other quality issues. This article is an up-to-date review of the challenges encountered during different stages of biopharmaceutical production and mitigation of problems arising during their development, formulation, manufacturing, and administration. It is a broad overview discussion of stability issues encountered during product life cycle i.e., upstream processing (aggregation, solubility, host cell proteins, color change), downstream bioprocessing (aggregation, fragmentation), formulation, manufacturing, and delivery to patients.

HPMCAS-Based Amorphous Solid Dispersions in Clinic: A Review on Manufacturing Techniques (Hot Melt Extrusion and Spray Drying), Marketed Products and Patents

Today, therapeutic candidates with low solubility have become increasingly common in pharmaceutical research pipelines. Several techniques such as hot melt extrusion, spray drying, supercritical fluid technology, electrospinning, KinetiSol, etc., have been devised to improve either or both the solubility and dissolution to enhance the bioavailability of these active substances belonging to BCS Class II and IV. The principle involved in all these preparation techniques is similar, where the crystal lattice of the drug is disrupted by either the application of heat or dissolving it in a solvent and the movement of the fine drug particles is arrested with the help of a polymer by either cooling or drying to remove the solvent. The dispersed drug particles in the polymer matrix have higher entropy and enthalpy and, thereby, higher free energy in comparison to the crystalline drug. Povidone, polymethaacrylate derivatives, hydroxypropyl methyl cellulose (HPMC) and hydroxypropyl methylcellulose acetate succinate derivatives are commonly used as polymers in the preparation of ASDs. Specifically, hydroxypropylmethylcellulose acetate succinate (HPMCAS)-based ASDs have become well established in commercially available products and are widely explored to improve the solubility of poorly soluble drugs. This article provides an analysis of two widely used manufacturing techniques for HPMCAS ASDs, namely, hot melt extrusion and spray drying. Additionally, details of HPMCAS-based ASD marketed products and patents have been discussed to emphasize the commercial aspect.

Effect of Atomic Layer Coating on the Stability of Solid Myoglobin Formulations

The effects of atomic layer (ALC) coating on physical properties and storage stability were examined in solid powders containing myoglobin, a model protein. Powders containing myoglobin and mannitol (1:1 w/w) were prepared by lyophilization or spray drying and subjected to aluminum oxide or silicon oxide ALC coating. Uncoated samples of these powders as well as coated and uncoated samples of myoglobin as received served as controls. After preparation (t0), samples were analyzed for moisture content, reconstitution time, myoglobin secondary structure, crystallinity, and protein aggregate content. Samples were stored for 3 months (t3) under controlled conditions (53% RH, 40 °C) in both open and closed vials and then analyzed as above. At t3, the recovery of soluble native (i.e., monomeric) protein depended on formulation, coating type, and drying method and was up to 2-fold greater in coated samples than in uncoated controls. Promisingly, some samples with high recovery also showed low soluble aggregate content (<10%) at t3 and low total monomer loss; the latter was correlated to sample moisture content. Overall, the results demonstrate that ALC coatings can stabilize solid protein formulations during storage, providing benefits over uncoated controls.

Synthesis of Multifunctional Protein-Polymer Conjugates via Oxygen-tolerant, Aqueous Copper-Mediated Polymerization, and Bioorthogonal Click Chemistry

Oxygen-tolerant, aqueous copper-mediated polymerization approaches are combined with click chemistry in either a sequential or a simultaneous manner, to enable the synthesis of multifunctional protein-polymer conjugates. Propargyl acrylate (PgA) and propargyl methacrylate (PgMA) grafting from a bovine serum albumin (BSA) macroinitiator is thoroughly optimized to synthesize chemically addressable BSA-poly(propargyl acrylate) and BSA-poly(propargyl methacrylate) respectively. The produced multifunctional bioconjugates bear pendant terminal 1-alkynes which can be readily post-functionalized via both [3+2] Huisgen cycloaddition and thiol-yne click chemistry under mild reaction conditions. Simultaneous oxygen-tolerant, aqueous copper-catalyzed polymerization, and click chemistry mediate the in situ multiple chemical tailoring of biomacromolecules in excellent yields.

Rationally Tailored Mesoporous Hosts for Optimal Protein Encapsulation

Proteins play important roles in the therapeutic, medical diagnostic, and chemical catalysis industries. However, their potential is often limited by their fragile and dynamic nature outside cellular environments. The encapsulation of proteins in solid materials has been widely pursued as a route to enhance their stability and ease of handling. Nevertheless, the experimental investigation of protein interactions with rationally designed synthetic hosts still represents an area in need of improvement. In this work, we leveraged the tunability and crystallinity of metal-organic frameworks (MOFs) and developed a series of crystallographically defined protein hosts with varying chemical properties. Through systematic studies, we identified the dominating mechanisms for protein encapsulation and developed a host material with well-tailored properties to effectively encapsulate the protein ubiquitin. Specifically, in our mesoporous hosts, we found that ubiquitin encapsulation is thermodynamically favored. A more hydrophilic encapsulation environment with favorable electrostatic interactions induces enthalpically favored ubiquitin-MOF interactions, and a higher pH condition reduces the intraparticle diffusion barrier, both leading to a higher protein loading. Our findings provide a fundamental understanding of host-guest interactions between proteins and solid matrices and offer new insights to guide the design of future protein host materials to achieve optimal protein loading. The MOF modification technique used in this work also demonstrates a facile method to develop materials easily customizable for encapsulating proteins with different surface properties.

Effect of Buffer Salts on Physical Stability of Lyophilized and Spray-Dried Protein Formulations Containing Bovine Serum Albumin and Trehalose

This study examined the effect of buffer salts on the physical stability of spray-dried and lyophilized formulations of a model protein, bovine serum albumin (BSA). BSA formulations with various buffers were dried by either lyophilization or spray drying. The protein powders were then characterized using solid-state Fourier transform infrared spectroscopy (ssFTIR), powder X-ray diffraction (PXRD), size exclusion chromatography (SEC), solid-state hydrogen/deuterium exchange with mass spectrometry (ssHDX-MS), and solid-state nuclear magnetic resonance spectroscopy (ssNMR). Particle characterizations such as Brunauer-Emmett-Teller (BET) surface area, particle size distribution, and particle morphology were also performed. Results from conventional techniques such as ssFTIR did not exhibit correlations with the physical stability of studied formulations. Deconvoluted peak areas of deuterated samples from the ssHDX-MS study showed a satisfactory correlation with the loss of the monomeric peak area measured by SEC (R2 of 0.8722 for spray-dried formulations and 0.8428 for lyophilized formulations) in the 90-day accelerated stability study conducted at 40°C. mDSC and PXRD was unable to measure phase separation in the samples right after drying. In contrast, ssNMR successfully detected the occurrence of phase separation between the succinic buffer component and protein in the lyophilized formulation, which results in a distribution of microenvironmental acidity and the subsequent loss of long-term stability. Moreover, our results suggested that buffer salts have less impact on physical stability for the spray-dried formulations than the lyophilized solids.

Isothermal denaturation fluorimetry vs Differential scanning fluorimetry as tools for screening of stabilizers for protein freeze-drying: human phenylalanine hydroxylase as the case study

The structural maintenance of therapeutic proteins during formulation and/or storage is a critical aspect, particularly for multi-domain and/or multimeric proteins which usually exhibit intrinsic structural dynamics leading to aggregation with concomitant loss-of-function. Protein freeze-drying is a widely used technique to preserve protein structure and function during storage. To minimize chemical/physical stresses occurring during this process, protein stabilizers are usually included, their effect being strongly dependent on the target protein. Therefore, they should be screened for on a time-consuming case-by-case basis. Herein, differential scanning fluorimetry (DSF) and isothermal denaturation fluorimetry (ITDF) were employed to screen, among different classes of freeze-drying additives, for the most effective stabilizer of the model protein human phenylalanine hydroxylase (hPAH). Correlation studies among retrieved DSF and ITDF parameters with recovered enzyme amount and activity indicated ITDF as the most appropriate screening method. Biochemical and biophysical characterization of hPAH freeze-dried with ITDF-selected stabilizers and a long-term storage study (12 months, 5 ± 3 °C) showed that the selected compounds prevented protein aggregation and preserved hPAH structural and functional properties throughout time storage. Our results provide a solid basis towards the choice of ITDF as a high-throughput screening step for the identification of protein freeze-drying protectors.

A Comprehensive Review of mRNA Vaccines

mRNA vaccines have been demonstrated as a powerful alternative to traditional conventional vaccines because of their high potency, safety and efficacy, capacity for rapid clinical development, and potential for rapid, low-cost manufacturing. These vaccines have progressed from being a mere curiosity to emerging as COVID-19 pandemic vaccine front-runners. The advancements in the field of nanotechnology for developing delivery vehicles for mRNA vaccines are highly significant. In this review we have summarized each and every aspect of the mRNA vaccine. The article describes the mRNA structure, its pharmacological function of immunity induction, lipid nanoparticles (LNPs), and the upstream, downstream, and formulation process of mRNA vaccine manufacturing. Additionally, mRNA vaccines in clinical trials are also described. A deep dive into the future perspectives of mRNA vaccines, such as its freeze-drying, delivery systems, and LNPs targeting antigen-presenting cells and dendritic cells, are also summarized.

Enhanced Stability of Vegetal Diamine Oxidase with Trehalose and Sucrose as Cryoprotectants: Mechanistic Insights

Enteric dysfunctions are common for various histamine-related intestinal disorders. Vegetal diamine oxidase (vDAO), an enzyme able to decompose histamine and thus alleviate histamine-related dysfunctions, was formulated in gastro-resistant tablet forms for oral administration as a food supplement and possible therapeutic agent. A major challenge for the use of proteins in the pharmaceutical field is their poor stability. In this study, vDAO was freeze-dried in the absence or in the presence of sucrose or trehalose as cryoprotectants and then formulated as tablets by direct compression. The stability of the obtained preparations was followed during storage at 4 °C and -20 °C for 18 months. In vitro dissolution tests with the vDAO powders formulated as tablets were performed in simulated gastric and in simulated intestinal fluids. The tablets obtained with the powder of the vDAO lyophilized with sucrose or trehalose cryoprotectants offered better protection for enzyme activity. Furthermore, the release of the vDAO lyophilized with the cryoprotectants was around 80% of the total loaded activity (enzyme units) compared to 20% for the control (vDAO powder prepared without cryoprotectants). This report revealed the potential of sucrose and trehalose as cryoprotectants to protect vDAO from freeze-drying stress and during storage, and also to markedly improve the vDAO release performance of tablets obtained with vDAO powders.

A Preclinical Study Comparing the Activity and Potency of OnabotulinumtoxinA and PrabotulinumtoxinA

Objective

The goal of this study was to compare the unit-to-unit biological activity of the vacuum-dried formulation of prabotulinumtoxinA (prabotA) and onabotulinumtoxinA (onabotA) in preclinical assays.

Methods

Reconstituted 100 U vials of prabotA and onabotA were tested in 3 distinct assays: plate-capture light chain activity (PC-LCA), measuringlight chain enzymatic activity after recovery of toxin from reconstituted product using a proprietary toxin capture step; cell-based potency assay (CBPA), measuring the intoxication steps of binding, translocation, and light chain activity (synaptosomal-associated protein 25 [SNAP25] cleavage); and mouse Digit Abduction Score (DAS), evaluating muscle paresis. Each assay tested 3 separate prabotA and onabotA lots on several independent test dates.

Results

Multiple orthogonal assays established that when assessed on a unit-to-unit basis, the biological activity of prabotA is lower than that of onabotA. In the PC-LCA and CBPA assays, onabotA displayed 1.51 ± 0.14-fold higher (mean ± SD) and 1.33 ± 0.07-fold higher (mean of pooled lots ± SEM) activity than prabotA, respectively. Similarly, the mouse DAS data showed that onabotA had 1.4 ± 0.1-fold higher (mean ± SEM) potency than prabotA. Results of all 3 assays demonstrated differences in potency, efficacy, and duration of action between onabotA and prabotA on a unit-to-unit basis.

Conclusion

Preclinical assays established differences in the biological activity of onabotA and prabotA, supporting that the units of biological activity are not interchangeable.

Recent progress in drying technologies for improving the stability and delivery efficiency of biopharmaceuticals

Background

Most biopharmaceuticals are developed in liquid dosage forms that are less stable than solid forms. To ensure the stability of biopharmaceuticals, it is critical to use an effective drying technique in the presence of an appropriate stabilizing excipient. Various drying techniques are available for this purpose, such as freeze drying or lyophilization, spray drying, spray freeze-drying, supercritical fluid drying, particle replication in nonwetting templates, and fluidized bed drying.

Area covered

In this review, we discuss drying technologies and their applications in the production of stable solid-state biopharmaceuticals, providing examples of commercially available products or clinical trial formulations. Alongside this, we also review how different analytical methods may be utilized in the evaluation of aerosol performance and powder characteristics of dried protein powders. Finally, we assess the protein integrity in terms of conformational and physicochemical stability and biological activity.

Expert opinion

With the aim of treating either infectious respiratory diseases or systemic disorders, inhaled biopharmaceuticals reduce both therapeutic dose and cost of therapy. Drying methods in the presence of optimized protein/stabilizer combinations, produce solid dosage forms of proteins with greater stability. A suitable drying method was chosen, and the process parameters were optimized based on the route of protein administration. With the ongoing trend of addressing deficiencies in biopharmaceutical production, developing new methods to replace conventional drying methods, and investigating novel excipients for more efficient stabilizing effects, these products have the potential to dominate the pharmaceutical industry in the future.

Instability Challenges and Stabilization Strategies of Pharmaceutical Proteins

Maintaining the structure of protein and peptide drugs has become one of the most important goals of scientists in recent decades. Cold and thermal denaturation conditions, lyophilization and freeze drying, different pH conditions, concentrations, ionic strength, environmental agitation, the interaction between the surface of liquid and air as well as liquid and solid, and even the architectural structure of storage containers are among the factors that affect the stability of these therapeutic biomacromolecules. The use of genetic engineering, side-directed mutagenesis, fusion strategies, solvent engineering, the addition of various preservatives, surfactants, and additives are some of the solutions to overcome these problems. This article will discuss the types of stress that lead to instabilities of different proteins used in pharmaceutics including regulatory proteins, antibodies, and antibody-drug conjugates, and then all the methods for fighting these stresses will be reviewed. New and existing analytical methods that are used to detect the instabilities, mainly changes in their primary and higher order structures, are briefly summarized.

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.

Mechano-bioconjugation Strategy Empowering Fusion Protein Therapeutics with Aggregation Resistance, Prolonged Circulation, and Enhanced Antitumor Efficacy

Bioconjugation is a powerful protein modification strategy to improve protein properties. Herein, we report mechano-bioconjugation as a novel approach to empower fusion protein therapeutics and demonstrate its utility by a protein heterocatenane (cat-IFN-ABD) containing interferon-α2b (IFN) mechanically interlocked with a consensus albumin-binding domain (ABD). The conjugate was selectively synthesized in cellulo following a cascade of post-translational events using a pair of heterodimerizing p53dim variants and two orthogonal split-intein reactions. The catenane topology was proven by combined techniques of LC-MS, SDS-PAGE, SEC, and controlled proteolytic digestion. Not only did cat-IFN-ABD retain activities comparable to those of the wild-type IFN and ABD, the conjugate also exhibited enhanced aggregation resistance and prolonged circulation time over the simple linear and cyclic fusions. Consequently, cat-IFN-ABD potently inhibited tumor growth in the mouse xenograft model. Therefore, mechano-bioconjugation by catenation accomplishes function integration with additional benefits, providing an alternative pathway for developing advanced protein therapeutics.

Recent advances in coiled-coil peptide materials and their biomedical applications

Extensive research has gone into deciphering the sequence requirements for peptides to fold into coiled-coils of varying oligomeric states. More recently, additional signals have been introduced within coiled-coils to promote higher order assembly into biomaterials with a rich distribution of morphologies. Herein we describe these strategies for association of coiled-coil building blocks and biomedical applications. With many of the systems described herein having proven use in protein storage, cargo binding and delivery, three dimensional cell culturing and vaccine development, the future potential of coiled-coil materials to have significant biomedical impact is highly promising.

Biosimilar monoclonal antibodies: Challenges and approaches towards formulation

Many biologic drug products, particularly monoclonal antibodies (mAbs), were off-patented between 2015 and 2020, and this process is continuing as the number of biologics approvals has increased. However, the availability of affordable biosimilars is delayed by secondary patents related to the formulation and manufacturing process. Therefore, an alternative formulation development is required to avoid infringement of formulation related patents. Several variables must be considered while developing alternative non-infringement formulations, including the time gap between the expiration of the molecule patent and the formulation patent, the ability not to infringe other secondary patents (process-related), and project timelines. As a part of life cycle management, innovator companies are adopting multiple strategies to delay biosimilar competition. Biosimilar companies could use the innovator formulation knowledge space to develop alternative formulations at the expense of time and cost. The present review discusses the key approaches in biosimilar formulation development, and further summarizes the use of innovator formulation knowledge space for biosimilar mAbs product development.

Single Molecule Fingerprinting Reveals Different Amplification Properties of α-Synuclein Oligomers and Preformed Fibrils in Seeding Assay

The quantification of α-synuclein aggregates has emerged as a promising biomarker for synucleinopathies. Assays that amplify and detect such aggregates have revealed the presence of seeding-competent species in biosamples of patients diagnosed with Parkinson's disease. However, multiple species, such as oligomers and amyloid fibrils, are formed during the aggregation of α-synuclein; these species are likely to coexist in biological samples, and thus it remains unclear which species(s) are contributing to the signal detected in seeding assays. To identify individual contributions to the amplification process, recombinant oligomers and preformed fibrils were produced and purified to characterize their individual biochemical and seeding potential. Here, we used single molecule spectroscopy to track the formation and purification of oligomers and fibrils at the single particle level and compare their respective seeding potential in an amplification assay. Single molecule detection validates that size-exclusion chromatography efficiently separates oligomers from fibrils. Oligomers were found to be seeding-competent, but our results reveal that their seeding behavior is very different compared to that of preformed fibrils, in our amplification assay. Overall, our data suggest that even a low number of preformed fibrils present in biosamples is likely to dominate the response in seeding assays.

Effect of Trehalose on the Physicochemical Properties of Freeze-Dried Powder of Royal Jelly of Northeastern Black Bee

Trehalose is known for its effect of improving the stability of freeze-dried foods. In this work, vacuum freeze-drying (VFD) technology was employed to prepare northeast black bee royal jelly into lyophilized powder and a novel method mixing trehalose into royal jelly is successfully developed to enhance the free radical scavenging ability and the nutrition stability of royal jelly lyophilized powder. The effects of different trehalose content (0, 0.1, 0.3, 0.5, 0.7 and 0.9 wt.%) on the physicochemical properties of lyophilized royal jelly powder were studied. With systematic analysis, it was found that the incorporation of suitable trehalose content in lyophilized royal jelly powder can reduce the loss of the protein, total sugar, total flavone content during the VFD process and enhance the total phenolic antioxidant capacity, solubility, angle of repose, and bulk density of the royal jelly powder. Finally, lyophilized royal jelly with 0.5 wt.% trehalose is selected as the suitable addition content which exhibits the best radical scavenging ability as well as the lowest hygroscopicity. From the perspective of sensory evaluation, all royal jelly lyophilized powders with trehalose are acceptable.

Evaluation of intermolecular interactions required for thermostability of a recombinant adenovirus within a film matrix

Thermostability of vaccines and biologic drugs are key to increasing global access to a variety of life-saving agents. In this report, we characterize interactions between a novel zwitterionic surfactant and adenovirus serotype 5 which allow the virus to remain stable at room temperature in a thin film matrix. Complexity of the adenovirus capsid and the polydispersity of the surfactant required use of a variety of techniques to achieve this goal. The CMC of the surfactant in Tris buffer (pH 6.5) was estimated to be 0.7-1.17 × 10^-4 M by the pyrene 1:3 ratio method. TEM images depict micelle formation around virus capsids. An estimated Kd of the virus-surfactant interaction of 2.25 × 10^-9 M was determined by isothermal titration calorimetry. Associated data suggest that this interaction may be thermodynamically favorable and entropically driven. A competitive saturation study and TEM images indicate that the surfactant also binds to hexon proteins on the virus capsid. Taken together, these data support the working hypothesis that the surfactant is capable of forming micelles in the solid and liquid state and that it forms a protective coating around the virus by binding to hexon proteins on the virus capsid during the film forming process.

X-ray imaging: A potential enabler of automated particulate detection and cake-structure analysis in lyophilized products?

The presence of particulate matter in parenteral products is a major concern since it affects the patients' safety and is one of the main reasons for product recalls. Conventional quality control is based on a visual inspection, which is a labour-intensive task. Limited to clear solutions and the surface of lyophilised products, it cannot be applied to opaque containers. This study assesses the application of X-ray imaging for detecting the particulate matter in a pharmaceutical lyophilized product. The most common types of particulates (i.e., steel, glass, lyo stopper, polymers and organics in different size classes) were intentionally spiked in vials. After optimizing all relevant parameters of the X-ray set-up, all classes of particulates were detected. At the same time, due to contrast enhancement, the inherent structures of lyophilized cake became obvious. This work addresses the potential and limits of X-ray technology in that regard, paving the way for automated image-based particulate matter detection. Moreover, this paper discusses using this approach to predict critical quality attributes (CQAs) of the drug product based on the cake structure attributes.

Calorimetric Investigation of the Relaxation Phenomena in Amorphous Lyophilized Solids

Studying the thermal history and relaxation of solid amorphous drug product matrices by calorimetry is a well-known approach, particularly in the context of correlating the matrix parameters with the long-term stability of freeze-dried protein drug products. Such calorimetric investigations are even more relevant today, as the application of new process techniques in freeze-drying (which strongly influence the thermal history of the products) has recently gained more interest. To revive the application of calorimetric methods, the widely scattered knowledge on this matter is condensed into a review and completed with new experimental data. The calorimetric methods are applied to recent techniques in lyophilization, such as controlled nucleation and aggressive/collapse drying. Phenomena such as pre-Tg events in differential scanning calorimetry and aging shoulders in isothermal microcalorimetry are critically reviewed and supplemented with data of freeze-dried products that have not been characterized with these methods before.

Enzymatic characterization of D-lactate dehydrogenase and application in alanine aminotransferase activity assay kit

D-lactate dehydrogenase (D-LDH) is widely used for the clinical detection of alanine aminotransferase (ALT) activity. It is a key enzyme in ALT detection kits, and its enzymatic properties directly determine sensitivity and accuracy of such kits. In this study, D-lactate dehydrogenase (WP_011543503, ldLDH) coding sequence derived from Lactobacillus delbrueckii was obtained from the NCBI database by gene mining. LdLDH was expressed and purified in Escherichia coli, and its enzyme activity, kinetic parameters, optimum temperature, and pH were characterized. Furthermore, stabilizers, including sugars, polyols, amino acids, certain salts, proteins, and polymers, were screened to improve stability of ldLDH during freeze-drying and storage. Finally, a kit based on ldLDH was tested to determine whether the enzyme had potential clinical applications. The results showed that ldLDH had a specific activity of 1,864 U/mg, K_m value of 1.34 mM, optimal reaction temperature of 55°C, and an optimal pH between 7.0 and 7.5. When sucrose or asparagine was used as a stabilizer, freeze-dried ldLDH remained stable at 37°C for > 2 months without significant loss of enzymatic activity. These results indicated that ldLDH possesses high activity and stability. Test results using the ALT assay kit prepared with ldLDH were consistent with those of commercial kits, with a relative deviation <5%. These results indicated that ldLDH met the primary requirements for ALT assays, laying a foundation for the development of new ALT kits with potential clinical applications.

PLGA/PLA-Based Long-Acting Injectable Depot Microspheres in Clinical Use: Production and Characterization Overview for Protein/Peptide Delivery

Over the past few decades, long acting injectable (LAI) depots of polylactide-co-glycolide (PLGA) or polylactic acid (PLA) based microspheres have been developed for controlled drug delivery to reduce dosing frequency and to improve the therapeutic effects. Biopharmaceuticals such as proteins and peptides are encapsulated in the microspheres to increase their bioavailability and provide a long release period (days or months) with constant drug plasma concentration. The biodegradable and biocompatible properties of PLGA/PLA polymers, including but not limited to molecular weight, end group, lactide to glycolide ratio, and minor manufacturing changes, could greatly affect the quality attributes of microsphere formulations such as release profile, size, encapsulation efficiency, and bioactivity of biopharmaceuticals. Besides, the encapsulated proteins/peptides are susceptible to harsh processing conditions associated with microsphere fabrication methods, including exposure to organic solvent, shear stress, and temperature fluctuations. The protein/peptide containing LAI microspheres in clinical use is typically prepared by double emulsion, coacervation, and spray drying techniques. The purpose of this review is to provide an overview of the formulation attributes and conventional manufacturing techniques of LAI microspheres that are currently in clinical use for protein/peptides. Furthermore, the physicochemical characteristics of the microsphere formulations are deliberated.