Modernizing Pharmaceutical Manufacturing: from Batch to Continuous Production

Control oriented modeling of twin-screw granulation in the ConsiGmaTM-25 production plant

ConsiGma^TM-25 is a continuous production plant integrating a twin-screw granulation, fluid bed drying, granule conditioning, and a tableting unit. The particle size distribution (PSD), active pharmaceutical ingredient (API) content, and liquid content of wet granules after twin-screw granulation affect the quality of intermediate and final products. This paper proposes methods for real-time monitoring of these quantities and control-oriented modeling of the granulator. The PSD of wet granules is monitored via an in-line process analytical technology (PAT) probe based on the spatial velocimetry principle. The algorithm for signal processing and evaluation of PSD characteristics is developed and applied to the acquired PSD data. A dynamic process model predicting PSD characteristics from granulation parameters is trained via the local linear model tree (LoLiMoT) approach. The experimental data required for the model training are collected via systematically designed excitation runs. Finally, the performance of the identified model is examined and verified by means of a new set of validation runs. Furthermore, an in-line PAT probe based on Raman spectroscopy is developed and integrated after the granulator. The API- and liquid content of produced wet granules are evaluated from the spectral data by means of chemometric modeling, and chemometric models are validated on a separate set of experimental data. The solutions proposed in this research can be used as a reliable (and necessary) basis for the development of advanced quality-by-design control concepts (e.g., PSD process control). Such concepts would ultimately improve the ConsiGma^TM-25 process performance in terms of robustness against disturbances and quality of intermediate and final products.

Evaluation of the influence of material properties and process parameters on granule porosity in twin-screw wet granulation

In recent years, continuous twin-screw wet granulation (TSWG) is gaining increasing interest from the pharmaceutical industry. Despite the many publications on TSWG, only a limited number of studies focused on granule porosity, which was found to be an important granule property affecting the final tablet quality attributes, e.g. dissolution. In current study, the granule porosity along the length of the twin-screw granulator (TSG) barrel was evaluated. An experimental set-up was used allowing the collection of granules at the different TSG compartments. The effect of active pharmaceutical ingredient (API) properties on granule porosity was evaluated by using six formulations with a fixed composition but containing APIs with different physical-chemical properties. Furthermore, the importance of TSWG process parameters liquid-to-solid (L/S) ratio, mass feed rate and screw speed for the granule porosity was evaluated. Several water-related properties as well as particle size, density and flow properties of the API were found to have an important effect on granule porosity. While the L/S ratio was confirmed to be the dictating TSWG process parameter, granulator screw speed was also found to be an important process variable affecting granule porosity. This study obtained crucial information on the effect of material properties and process parameters on granule porosity (and granule formation) which can be used to accelerate TSWG process and formulation development.

Elucidation of Granulation Mechanisms along the Length of the Barrel in Continuous Twin-Screw Melt Granulation

In the pharmaceutical industry, innovative continuous manufacturing technologies such as twin-screw melt granulation (TSMG) are gaining more and more interest to process challenging formulations. To enable the implementation of TSMG, more elucidation of the process is required and this study provides a better understanding of the granule formation along the length of the barrel. By sampling at four different zones, the influence of screw configuration, process parameters and formulation is investigated for the granule properties next to the residence time distribution. It showed that conveying elements initiate the granulation by providing a limited heat transfer into the powder bed. In the kneading zones, the consolidation stage takes place, shear elongation combined with breakage and layering is occurring for the reversed configurations and densification with breakage and layering for the forward and neutral configurations. Due to the material build-up in the reversed configurations, these granules are larger, stronger, more elongated and less porous due to the higher degree of shear and densification. This configuration also shows a significantly longer residence time compared to the forward configuration. Hence, the higher level of shear and the longer period of time enables more melting of the binder resulting in successful granulation.

From Batch to the Semi-Continuous Flow Hydrogenation of pNB, pNZ-Protected Meropenem

Meropenem is currently the most common carbapenem in clinical applications. Industrially, the final synthetic step is characterized by a heterogeneous catalytic hydrogenation in batch mode with hydrogen and Pd/C. The required high-quality standard is very difficult to meet and specific conditions are required to remove both protecting groups [i.e., p-nitrobenzyl (pNB) and p-nitrobenzyloxycarbonyl (pNZ)] simultaneously. The three-phase gas-liquid-solid system makes this step difficult and unsafe. The introduction of new technologies for small-molecule synthesis in recent years has opened up new landscapes in process chemistry. In this context, we have investigated meropenem hydrogenolysis using microwave (MW)-assisted flow chemistry for use as a new technology with industrial prospects. The reaction parameters (catalyst amount, T, P, residence time, flow rate) in the move from the batch process to semi-continuous flow were investigated under mild conditions to determine their influence on the reaction rate. The optimization of the residence time (840 s) and the number of cycles (4) allowed us to develop a novel protocol that halves the reaction time compared to batch production (14 min vs. 30 min) while maintaining the same product quality. The increase in productivity using this semi-continuous flow technique compensates for the slightly lower yield (70% vs. 74%) obtained in batch mode.

Comparing Integrated Continuous Process "LaVortex®" and Conventional Batch Processes for the Pharmaceutical Manufacturing of Acetaminophen Oral Dosage Formulations: Challenges and Pharmaceutical Properties of the Granular and Tableted Products

LaVortex® was developed as a novel free-flow continuous granulation/drying (CGD) system. In this study, we compared the advantages and disadvantages of granules prepared by continuous and batchwise manufacturing systems. Granules containing 30 % acetaminophen were manufactured under various operating conditions using CGD system, with comparison granules manufactured using conventional batch systems that involve a combination of fluid bed granulation (FG), agitation granulation (AG), continuous drying, fluid bed drying, and/or shelf drying, after which the pharmaceutical properties of each type of manufactured granule were evaluated. Cumulative particle-size distributions were determined by sieving, powder flowabilities were determined by angle of repose measurements, and scanning electron microscopy was employed to examine granule morphologies. The CGD system produced fine-to-large spherical or ellipsoidal granules that exhibited excellent powder fluidities and tabletabilities that are almost identical to those of AG granules. Moreover, the CGD granules exhibited better powder flowability than the FG granules. The addition of water promoted CGD-granule growth and improved significantly powder flowability, and did a little in tabletability. Small spherical granules with good fluidity suitable for fine-particle-coating core materials, or large granules with excellent fluidity and tabletability, were prepared by adjusting the values of the elemental parameters of the CGD process.

Implementation of a Fully Integrated Continuous Manufacturing Line for Direct Compression and Coating at a Commercial Pharmaceutical Facility - Part 1: Operational Considerations and Control Strategy

We implement a fully integrated continuous manufacturing (CM) line for direct compression and coating of a pharmaceutical oral solid dosage form in a commercial production facility. In this first paper of a two-part series, we describe process design and operational choices made to introduce CM using infrastructure originally intended for batch operations. Consistent with lean manufacturing principles, we select equipment, facilities, and novel process analytical technologies that meet production agility goals alongside an existing batch process. Choices address process risks, are aligned with existing quality systems, yet allow exploration of CM agility benefits in commercial operations. We outline how operating procedures, control schemes, and release criteria from the historical batch process are adapted for CM with modified lot and yield definitions based on patient demand. We devise a hierarchy of complementary controls including real-time process interrogation, predictive residence time distribution models of tablet concentration, real-time product release testing using automated tablet NIR spectroscopy, active rejection and diversion, and throughput-based sampling. Results from lots produced under normal operational conditions confirm our CM process provides assurance of product quality. Qualification strategies to achieve lot size flexibility aims are also described. Finally, we consider CM extensions to formulations with differing risk profiles. Further analysis of results for lots produced under normal operational conditions is provided in part 2 (Rosas 2022).

Enhanced blend uniformity and flowability of low drug loaded fine API blends via dry coating: The effect of mixing time and excipient size

Although previous research demonstrated improved flowability, packing, fluidization, etc. of individual powders via nanoparticle dry coating, none considered its impact on very low drug loaded blends. Here, fine ibuprofen at 1, 3, and 5 wt% drug loadings (DL) was used in multi-component blends to examine the impact of the excipients size, dry coating with hydrophilic or hydrophobic silica, and mixing times on the blend uniformity, flowability and drug release rates. For uncoated active pharmaceutical ingredients (API), the blend uniformity (BU) was poor for all blends regardless of the excipient size and mixing time. In contrast, for dry coated API having low agglomerate ratio (AR), BU was dramatically improved, more so for the fine excipient blends, at lesser mixing times. For dry coated API, the fine excipient blends mixed for 30 min had enhanced flowability and lower AR; better for the lowest DL having lesser silica, likely due to mixing induced synergy of silica redistribution. For the fine excipient tablets, dry coating led to fast API release rates even with hydrophobic silica coating. Remarkably, the low AR of the dry coated API even at very low DL and amounts of silica in the blend led to the enhanced blend uniformity, flow, and API release rate.

Compact capillary high performance liquid chromatography system for pharmaceutical on-line reaction monitoring

Due to their size, conventional high performance liquid chromatographs (HPLCs) are difficult to place close to a reaction vessel within a pharmaceutical manufacturing or development site. Typically, long transfer lines are required to move sample from the reactor to the HPLC for analysis and high solvent usage is required. However, herein a compact and modular separation system has been developed to enable co-location of an HPLC with a small-scale reactor for reaction monitoring in the synthesis of active pharmaceutical ingredients. Using a framework based on capillary HPLC, a compact gradient separation system with a fully modular architecture is described. A custom miniature diode-array detector with a linear dynamic range (up to 1500 mAU at 210 nm) was integrated and evaluated for on-line reaction monitoring. In evaluating system suitability, average peak area %RSD of <3%, and an average retention time %RSD of <0.7%, were achieved. To demonstrate practical utility, the compact system was coupled directly to an on-line lab-scale flow through reactor for continuous reaction monitoring in the laboratory fume hood, where a study of the 3rd Bourne reaction was used to compare the performance of the compact system with a commercially available process HPLC instrument (Waters PATROL UPLC). Further, 33 off-line samples from a continuous crystallization reactor were analysed and it was found that the developed compact HPLC system showed equivalent quantitative performance to an Agilent 1290 Infinity II HPLC system.

Direct Tableting on a Continuous Manufacturing Line-Impact of Mixing Parameters, Material Densities, and Drug Load on Subsequent Process Parameters and Tablet Quality

The continuous manufacturing (CM) of solid oral dosage forms has received increased attention in recent years and has become a leading technology in the pharmaceutical industry. A model has been developed based on process data from two design of experiments (DoEs), where the impact of the mixer process parameters, throughput (THR), hold up mass (HUM), impeller speed (IMP), and the input raw material bulk density (BD_i), on the continuous process and the resulting drug product has been investigated. These statistical models revealed equations, describing process parameter interactions for optimization purposes. For the exit valve opening width (EV) at the bottom of the continuous mixer (CMT), the combination of high throughput (30 kg/h) and low impeller speed (300 rpm) resulted in optimal process conditions. Apparent bulk density of the blend (BD) within the process, fill depth (FD), and tensile strength (TS) were mainly impacted by input bulk density (BD_i) of the tableting mixture, emphasizing the role of material attributes on the continuous manufacturing process. The apparent bulk density itself was, other than from the input bulk density, equally dependent from THR and IMP in opposite deflections. However, process parameters (THR and IMP) revealed a minor impact on the apparent BD compared to the input bulk density. FD was impacted mainly by THR ahead of IMP and the TS by IMP and THR to a similar extend, in opposite deflections. A simplified linear model to estimate the input bulk density revealed satisfactory prediction quality when included in the derived statistical model equations.

Recent developments and applications of selected ion flow tube mass spectrometry (SIFT-MS)

Selected ion flow tube mass spectrometry (SIFT-MS) is now recognized as the most versatile analytical technique for the identification and quantification of trace gases down to the parts-per-trillion by volume, pptv, range. This statement is supported by the wide reach of its applications, from real-time analysis, obviating sample collection of very humid exhaled breath, to its adoption in industrial scenarios for air quality monitoring. This review touches on the recent extensions to the underpinning ion chemistry kinetics library and the alternative challenge of using nitrogen carrier gas instead of helium. The addition of reagent anions in the Voice200 series of SIFT-MS instruments has enhanced the analytical capability, thus allowing analyses of volatile trace compounds in humid air that cannot be analyzed using reagent cations alone, as clarified by outlining the anion chemistry involved. Case studies are reviewed of breath analysis and bacterial culture volatile organic compound (VOC), emissions, environmental applications such as air, water, and soil analysis, workplace safety such as transport container fumigants, airborne contamination in semiconductor fabrication, food flavor and spoilage, drugs contamination and VOC emissions from packaging to demonstrate the stated qualities and uniqueness of the new generation SIFT-MS instrumentation. Finally, some advancements that can be made to improve the analytical capability and reach of SIFT-MS are mentioned.

Towards Antibiotic Synthesis in Continuous-Flow Processes

Continuous-flow chemistry has become a mainstream process and a notable trend among emerging technologies for drug synthesis. It is routinely used in academic and industrial laboratories to generate a wide variety of molecules and building blocks. The advantages it provides, in terms of safety, speed, cost efficiency and small-equipment footprint compared to analog batch processes, have been known for some time. What has become even more important in recent years is its compliance with the quality objectives that are required by drug-development protocols that integrate inline analysis and purification tools. There can be no doubt that worldwide government agencies have strongly encouraged the study and implementation of this innovative, sustainable and environmentally friendly technology. In this brief review, we list and evaluate the development and applications of continuous-flow processes for antibiotic synthesis. This work spans the period of 2012-2022 and highlights the main cases in which either active ingredients or their intermediates were produced under continuous flow. We hope that this manuscript will provide an overview of the field and a starting point for a deeper understanding of the impact of flow chemistry on the broad panorama of antibiotic synthesis.

Semi-mechanistic reduced order model of pharmaceutical tablet dissolution for enabling Industry 4.0 manufacturing systems

We propose a generalization of the Weibull dissolution model, referred to as generalized Weibull dissolution model, that seamlessly captures all three fractional dissolution rates experimentally observed in pharmaceutical solid tablets, namely decreasing, increasing, and non-monotonic rates. This is in contrast to traditional reduced order models, which capture at most two fractional dissolution rates and, thus, are not suitable for a wide range of product formulations hindering, for example, the adoption of knowledge management in the context of Industry 4.0. We extend the generalized Weibull dissolution model further to capture the relationship between critical process parameters (CPPs), critical materials attributes (CMAs), and dissolution profile to, in turn, facilitate real-time release testing (RTRT) and quality-by-control (QbC) strategies. Specifically, we endow the model with multivariate rational polynomials that interpolate the mechanistic limiting behavior of tablet dissolution as CPPs and CMAs approach certain values of physical significance (such as the upper and lower bounds of tablet porosity or lubrication conditions), thus the semi-mechanistic nature of the reduced order model. Restricting attention to direct compaction and using various case studies from the literature, we demonstrate the versatility and the capability of the semi-mechanistic ROM to estimate changes in dissolution due to process disturbances in tablet weight, porosity, lubrication conditions (i.e., the total amount of shear strain imparted during blending), and moisture content in the powder blend. In all of the cases considered in this work, the estimations of the model are in remarkable agreement with experimental data.

Elucidation of the powder flow pattern in a twin-screw LIW-feeder for various refill regimes

The importance of residence time distribution modeling is acknowledged as a tool for enabling material tracking and control within a continuous manufacturing line in order to safeguard both product quality and production efficiency. One of the first unit-operations into a continuous direct compression line (i.e. CDC-line) worthwhile doing extensive RTD-analysis upon are the LIW-feeders since they dose the ingredients in a controlled way following the label claim and hence can directly influence critical quality attributes like content uniformity. An NIR measurement method was developed determining the RTD of selected powders at specific feeder settings. Step-change experiments using sodium saccharin as a tracer were conducted. In order to gain and in depth understanding of the material flow, spatial samples throughout the hopper were taken at predefined timepoints during the step change experiments. This revealed the presence of a bypass trajectory along the edges of the agitator, while in the center of the agitator an inner mixing volume in which the tracer concentration lags behind seemed to be present. Finally, a model based on a plug flow and continuous stirred tank reactor was evaluated. The fitted model was not able to capture this complex flow behavior and shows the need for an extended compartmental model distinguishing between a bypass trajectory formed by the agitator and an inner mixing volume.

Inclusion Body Production in Fed-Batch and Continuous Cultivation

Various fermentation strategies in industrial biotechnology are applied to produce recombinant target proteins using Escherichia coli. These proteins are often expressed as inclusion bodies (IBs), resulting in a high purity, high stability, and high product titers. In state-of-the-art fed-batch processes, product formation takes place in a short period of time. Sterilization, cleaning, and biomass growth are time consuming steps and reduce the space-time yield. Thus, the interest in establishing continuous cultivations, facilitating higher space-time yields, has been increased in recent years. In this protocol, we provide information and a guide to set-up the production of recombinant proteins in fed-batch, as well as in chemostat continuous cultivations using E. coli.

Developing a Virtual Flowability Sensor for Monitoring a Pharmaceutical Dry Granulation Line

Current technologies to measure granule flowability involve at-line methods that can take hours to perform. This is problematic for a continuous dry granulation tableting line, where the quality assurance and control of the final tablet products depend on real-time monitoring and control of powder flowability. Hence, a real-time alternative is needed for measuring the flowability of the granular products coming out of the roller compactor, which is the unit operation immediately preceding the tablet press. Since particle analyzers have the potential to take inline measurements of the size and shape of granules, they can potentially serve as real-time flowability sensors, given that the size and shape measurements can be used to reliably predict flowability measurements. This paper reports on the use of Partial Least Squares (PLS) regression to utilize distributions of size and shape measurements in predicting the output of three different types of flowability measurements: rotary drum flow, orifice flow, and tapped density analysis. The prediction performance of PLS had a coefficient of determination ranging from 0.80 to 0.97, which is the best reported performance in the literature. This is attributed to the ability of PLS to handle high collinearity in the datasets and the inclusion of multiple shape characteristics-eccentricity, form factor, and elliptical form factor-into the model. The latter calls for a change in industry perspective, which normally dismisses the importance of shape in favor of size; and the former suggests the use of PLS as a better way to reduce the dimensionality of distribution datasets, instead of the widely used practice of pre-selecting distribution percentiles.

3D Printable Drug Delivery Systems: Next-generation Healthcare Technology and Regulatory Aspects

A revolutionary shift in healthcare has been sparked by the development of 3D printing, propelling us into an era replete with boundless opportunities for personalized DDS (Drug Delivery Systems). Precise control of the kinetics of drug release can be achieved through 3D printing, improving treatment efficacy and patient compliance. Additionally, 3D printing facilitates the co-administration of multiple drugs, simplifying treatment regimens. The technology offers rapid prototyping and manufacturing capabilities, reducing development timelines and costs. The seamless integration of advanced algorithms and artificial neural networks (ANN) augments the precision and efficacy of 3D printing, propelling us toward the forefront of personalized medicine. This comprehensive review delves into the regulatory frontiers governing 3D printable drug delivery systems, with an emphasis on adhering to rigorous safety protocols to ensure the well-being of patients by leveraging the latest advancements in 3D printing technologies powered by artificial intelligence. The paradigm promises superior therapeutic outcomes and optimized medication experiences and sets the stage for an immersive future within the Metaverse, wherein healthcare seamlessly converges with virtual environments to unlock unparalleled possibilities for personalized treatments.

Liposome manufacturing under continuous flow conditions: towards a fully integrated set-up with in-line control of critical quality attributes

Continuous flow manufacturing (CFM) has shown remarkable advantages in the industrial-scale production of drug-loaded nanomedicines, including mRNA-based COVID-19 vaccines. Thus far, CFM research in nanomedicine has mainly focused on the initial particle formation step, while post-formation production steps are hardly ever integrated. The opportunity to implement in-line quality control of critical quality attributes merits closer investigation. Here, we designed and tested a CFM setup for the manufacturing of liposomal nanomedicines that can potentially encompass all manufacturing steps in an end-to-end system. Our main aim was to elucidate the key composition and process parameters that affect the physicochemical characteristics of the liposomes. Total flow rate, lipid concentration and residence time of the liposomes in a high ethanol environment (i.e., above 20% v/v) emerged as critical parameters to tailor liposome size between 80 and 150 nm. After liposome formation, the pressure and the surface area of the filter in the ultrafiltration unit were critical parameters in the process of clearing the dispersion from residual ethanol. As a final step, we integrated in-line measurement of liposome size and residual ethanol content. Such in-line measurements allow for real-time monitoring and in-process adjustment of key composition and process parameters.

Continuous process technology for bottom-up synthesis of soluble cello-oligosaccharides by immobilized cells co-expressing three saccharide phosphorylases

BACKGROUND

Continuous processing with enzyme reuse is a well-known engineering strategy to enhance the efficiency of biocatalytic transformations for chemical synthesis. In one-pot multistep reactions, continuous processing offers the additional benefit of ensuring constant product quality via control of the product composition. Bottom-up production of cello-oligosaccharides (COS) involves multistep iterative β-1,4-glycosylation of glucose from sucrose catalyzed by sucrose phosphorylase from Bifidobacterium adeloscentis (BaScP), cellobiose phosphorylase from Cellulomonas uda (CuCbP) and cellodextrin phosphorylase from Clostridium cellulosi (CcCdP). Degree of polymerization (DP) control in the COS product is essential for soluble production and is implemented through balance of the oligosaccharide priming and elongation rates. A whole-cell E. coli catalyst co-expressing the phosphorylases in high yield and in the desired activity ratio, with CdP as the rate-limiting enzyme, was reported previously.

RESULTS

Freeze-thaw permeabilized E. coli cells were immobilized in polyacrylamide (PAM) at 37-111 mg dry cells/g material. PAM particles (0.25-2.00 mm size) were characterized for COS production (~ 70 g/L) in mixed vessel with catalyst recycle and packed-bed reactor set-ups. The catalyst exhibited a dry mass-based overall activity (270 U/g; 37 mg cells/g material) lowered by ~ 40% compared to the corresponding free cells due to individual enzyme activity loss, CbP in particular, caused by the immobilization. Temperature studies revealed an operational optimum at 30 °C for stable continuous reaction (~ 1 month) in the packed bed (volume: 40 mL; height: 7.5 cm). The optimum reflects the limits of PAM catalyst structural and biological stability in combination with the requirement to control COS product solubility in order to prevent clogging of the packed bed. Using an axial flow rate of 0.75 cm- 1, the COS were produced at ~ 5.7 g/day and ≥ 95% substrate conversion (sucrose 300 mM). The product stream showed a stable composition of individual oligosaccharides up to cellohexaose, with cellobiose (48 mol%) and cellotriose (31 mol%) as the major components.

CONCLUSIONS

Continuous process technology for bottom-up biocatalytic production of soluble COS is demonstrated based on PAM immobilized E. coli cells that co-express BaScP, CuCbP and CcCdP in suitable absolute and relative activities.

Digital Design of Filtration and Washing of Active Pharmaceutical Ingredients via Mechanistic Modeling

To facilitate integrated end-to-end pharmaceutical manufacturing using digital design, a model capable of transferring material property information between operations to predict product attributes in integrated purification processes has been developed. The focus of the work reported here combines filtration and washing operations used in active pharmaceutical ingredient (API) purification and isolation to predict isolation performance without the need of extensive experimental work. A fixed Carman-Kozeny filtration model is integrated with several washing mechanisms (displacement, dilution, and axial dispersion). Two limiting cases are considered: case 1 where there is no change in the solid phase during isolation (no particle dissolution and/or growth), and case 2 where the liquid and solid phases are equilibrated over the course of isolation. In reality, all actual manufacturing conditions would be bracketed by these two limiting cases, so consideration of these two scenarios provides rigorous theoretical bounds for assessing isolation performance. This modeling approach aims to facilitate the selection of most appropriate models suitable for different isolation scenarios, without the requirement to use overly complex models for straightforward isolation processes. Mefenamic acid and paracetamol were selected as representative model compounds to assess a range of isolation scenarios. In each case, the objective of the models was to identify the purity of the product reached with a fixed wash ratio and minimize the changes to the crystalline particle attributes that occur during the isolation process. This was undertaken with the aim of identifying suitable criteria for the selection of appropriate filtration and washing models corresponding to relevant processing conditions, and ultimately developing guidelines for the digital design of filtration and washing processes.

Batch versus continuous blending of binary and ternary pharmaceutical powder mixtures

The material properties of excipients and active pharmaceutical ingredients (API's) are important parameters that affect blend uniformity of pharmaceutical powder formulations. With the current shift from batch to continuous manufacturing in the pharmaceutical industry, blending of excipients and API is converted to a continuous process. The relation between material properties and blend homogeneity, however, is generally based on batch-wise blending trials. Limited information is available on how material properties affect blending performance in a continuous process. Here, blending of API and excipients is studied in both a batch and a continuous process. Homogeneity of the resulting mixtures is analyzed, which reveals that the impact of material properties is very different in a continuous process. Where parameters such as particle size, density and flowability have significant impact on blending performance in a traditional batch process, continuous blending is more robust resulting in uniform blends for a large variety of blend compositions.

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Continuous mixing improves blend uniformity of pharmaceutical powder mixtures.

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Blend uniformity is highly dependent on excipient properties in a batch process.

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Continuous mixing is more robust, with little impact of material properties.

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Powder bulk density strongly affects blend homogeneity in a batch process.

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Blending of low API dosages is more challenging in a continuous process.

Application of Twin-Screw Melt Granulation to Overcome the Poor Tabletability of a High Dose Drug

Pharmaceutical tablet manufacturing has seen a paradigm shift toward continuous manufacturing and twin-screw granulation-based technologies have catalyzed this shift. Twin-screw granulator can simultaneously perform unit operations like mixing, granulation, and drying of the granules. The present study investigates the impact of polymer concentration and processing parameters of twin-screw melt granulation, on flow properties and compaction characteristics of a model drug having high dose and poor tabletability. Acetaminophen (AAP) and polyvinylpyrrolidone vinyl acetate (PVPVA) were used as a model drug (90-95% w/w) and polymeric binder (5-10%w/w), respectively, for the current study. Feed rate (~650-1150 g/h), extruder screw speed (150-300 rpm), and temperature (60-150°C) were used as processing variables. Results showed the reduction in particle size of drug in the extrudates (D₉₀ of 15-25 μm from ~80 μm), irrespective of processing condition, while flow properties were a function of polymer concentration. Overall, good flowability of the products and their tablets with optimum tensile strength can be obtained through using high polymer concentration (i.e., 10% w/w), lower feed rate (~650 g/h), lower extruder screw speed (150 rpm), and higher processing temperatures (up to 120°C). The findings from the current study can be useful for continuous manufacturing of tablets of high dose drugs with minimal excipient loading in the final dosage form.

Continuous direct compression: Development of an empirical predictive model and challenges regarding PAT implementation

In this study, an empirical predictive model was developed based on the quantitative relationships between blend properties, critical quality attributes (CQA) and critical process parameters (CPP) related to blending and tableting. The blend uniformity and API concentration in the tablets were used to elucidate challenges related to the processability as well as the implementation of PAT tools. Thirty divergent ternary blends were evaluated on a continuous direct compression line (ConsiGma™ CDC-50). The trials showed a significant impact of the impeller configuration and impeller speed on the blending performance, whereas a limited impact of blend properties was observed. In contrast, blend properties played a significant role during compression, where changes in blend composition significantly altered the tablet quality. The observed correlations allowed to develop an empirical predictive model for the selection of process configurations based on the blend properties, reducing the number of trial runs needed to optimize a process and thus reducing development time and costs of new drug products. Furthermore, the trials elucidated several challenges related to blend properties that had a significant impact on PAT implementation and performance of the CDC-platform, highlighting the importance of further process development and optimization in order to solve the remaining challenges.

Scalable Advanced Li(Ni0.8Co0.1Mn0.1)O2 Cathode Materials from a Slug Flow Continuous Process

Li[Ni_0.8Co_0.1Mn_0.1]O₂ (LNCMO811) is the most studied cathode material for next-generation lithium-ion batteries with high energy density. However, available synthesis methods are time-consuming and complex, restricting their mass production. A scalable manufacturing process for producing NCM811 hydroxide precursors is vital for commercialization of the material. In this work, a three-phase slug flow reactor, which has been demonstrated for its ease of scale-up, better synthetic control, and excellent uniform mixing, was developed to control the initial stage of the coprecipitation of NCM811 hydroxide. Furthermore, an equilibrium model was established to predict the yield and composition of the final product. The homogeneous slurry from the slug flow system was obtained and then transferred into a ripening vessel for the necessary ripening process. Finally, the lithium-nickel-cobalt-manganese oxide was obtained through the calcination of the slug flow-derived precursor with lithium hydroxide, having a tap density of 1.3 g cm^-3 with a well-layered structure. As-synthesized LNCMO811 shows a high specific capacity of 169.5 mAh g^-1 at a current rate of 0.1C and a long cycling stability of 1000 cycling with good capacity retention. This demonstration provides a pathway toward scaling up the cathode synthesis process for large-scale battery applications.

Process intensification of atorvastatin calcium crystallization for target polymorph development via continuous combined cooling and antisolvent crystallization using an oscillatory baffled crystallizer

In this paper, continuous crystallization of Atorvastatin calcium (ASC) using a continuous oscillatory baffled crystallizer (COBC) has been investigated. Like most API manufacturing, ASC is manufactured batchwise and the pure API is recovered via batch combined cooling and antisolvent crystallization (CCAC) process, which has the challenges of low productivity, wide crystal size distribution (CSD) and sometimes polymorphic form contamination. To overcome the limitations of the batch crystallization, continuous crystallization of ASC was studied in a NiTech (United Kingdom) DN15 COBC, manufactured by Alconbury Weston Ltd. (AWL, United Kingdom), with the aim to improve productivity and CSD of the desired polymorph. The COBC has the advantage of high heat transfer rates and improved mixing that significantly reduces the crystallization time. It also has the advantage of spatial temperature distribution and multiple addition ports to control supersaturation and hence the crystallization process. This work uses an array of process analytical technology (PAT) tools to assess key process parameters that affect the polymorphic outcome and CSD. Two parameters were found to have significant impact on the polymorph, they are ratio of solvent to antisolvent at the point of mixing of the two streams and presence of seeds. The splitting of antisolvent into two addition ports in the COBC was found to give the desired form. The CCAC of ASC in COBC was found to be -30-fold more productive than the batch CCAC process. The cycle time for generating 100 g of desired polymorphic form of ASC also significantly reduced from 22 h in batch process to 12 min in the COBC. The crystals obtained using a CCAC process in a COBC had a narrower CSD compared to that from a batch crystallization process.

Bacterial extracellular vesicle applications in cancer immunotherapy

Cancer therapy is undergoing a paradigm shift toward immunotherapy focusing on various approaches to activate the host immune system. As research to identify appropriate immune cells and activate anti-tumor immunity continues to expand, scientists are looking at microbial sources given their inherent ability to elicit an immune response. Bacterial extracellular vesicles (BEVs) are actively studied to control systemic humoral and cellular immune responses instead of using whole microorganisms or other types of extracellular vesicles (EVs). BEVs also provide the opportunity as versatile drug delivery carriers. Unlike mammalian EVs, BEVs have already made it to the clinic with the meningococcal vaccine (Bexsero®). However, there are still many unanswered questions in the use of BEVs, especially for chronic systemically administered immunotherapies. In this review, we address the opportunities and challenges in the use of BEVs for cancer immunotherapy and provide an outlook towards development of BEV products that can ultimately translate to the clinic.

Nano-Dry-Melting: A Novel Technology for Manufacturing of Pharmaceutical Amorphous Solid Dispersions

Amorphous solid dispersions (ASD) are one of the most prominent formulation approaches to overcome bioavailability issues that are often presented by new poorly soluble drug candidates. State-of-the art manufacturing techniques include hot melt extrusion and solvent-based methods like spray drying. The high thermal and mechanical shear stress during hot melt extrusion, or the use of an organic solvent during solvent-based methods, are examples of clear drawbacks for those methods, limiting their applicability for certain systems. In this work a novel process technology is introduced, called Nano-Dry-Melting (NDM), which can provide an alternative option for ASD manufacturing. NDM consists of a comminution step in which the drug is ground to nanosize and a drying step provides a complete amorphization of the system at temperatures below the melting point. Two drug–polymer systems were prepared using NDM with a wet media mill and a spray dryer and analyzed regarding their degree of crystallinity using XRD analysis. Feasibility studies were performed with indomethacin and PVP. Furthermore, a “proof-of-concept” study was conducted with niclosamide. The experiments successfully led to amorphous samples at temperatures of about 50 K below the melting point within seconds of heat exposition. With this novel, solvent-free and therefore “green” production technology it is feasible to manufacture ASDs even with those drug candidates that cannot be processed by conventional process technologies.

Model Driven Design for Integrated Twin Screw Granulator and Fluid Bed Dryer via Flowsheet Modelling

This paper presents a flowsheet modelling of an integrated twin screw granulation (TSG) and fluid bed dryer (FBD) process using a Model Driven Design (MDD) approach. The MDD approach is featured by appropriate process models and efficient model calibration workflow to ensure the product quality. The design space exploration is driven by the physics of the process instead of extensive experimental trials. By means of MDD, the mechanistic-based process kernels are first defined for the TSG and FBD processes. With the awareness of the underlying physics, the complementary experiments are carried out with relevance to the kinetic parameters in the defined models. As a result, the experiments are specifically purposeful for model calibration and validation. The L/S ratio (liquid to solid ratio) and inlet air temperature are selected as the Critical Process Parameters (CPPs) in TSG and FBD for model validation, respectively. Global System Analysis (GSA) is further performed to assess the uncertainty of CPPs imposed on the Critical Quality Attributes (CQAs), which provides significant insights to the exploration of the design space considering both TSG and FBD process parameters.

Microfluidic Manufacture of Lipid-Based Nanomedicines

Nanoparticulate technologies have revolutionized drug delivery allowing for passive and active targeting, altered biodistribution, controlled drug release (temporospatial or triggered), enhanced stability, improved solubilization capacity, and a reduction in dose and adverse effects. However, their manufacture remains immature, and challenges exist on an industrial scale due to high batch-to-batch variability hindering their clinical translation. Lipid-based nanomedicines remain the most widely approved nanomedicines, and their current manufacturing methods remain discontinuous and face several problems such as high batch-to-batch variability affecting the critical quality attributes (CQAs) of the product, laborious multistep processes, need for an expert workforce, and not being easily amenable to industrial scale-up involving typically a complex process control. Several techniques have emerged in recent years for nanomedicine manufacture, but a paradigm shift occurred when microfluidic strategies able to mix fluids in channels with dimensions of tens of micrometers and small volumes of liquid reagents in a highly controlled manner to form nanoparticles with tunable and reproducible structure were employed. In this review, we summarize the recent advancements in the manufacturing of lipid-based nanomedicines using microfluidics with particular emphasis on the parameters that govern the control of CQAs of final nanomedicines. The impact of microfluidic environments on formation dynamics of nanomaterials, and the application of microdevices as platforms for nanomaterial screening are also discussed.

Linked experimental and modelling approaches for tablet property predictions

Recent years have seen the advent of Quality-by-Design (QbD) as a philosophy to ensure the quality, safety, and efficiency of pharmaceutical production. The key pharmaceutical processing methodology of Direct Compression to produce tablets is also the focus of some research. The traditional Design-of-Experiments and purely experimental approach to achieve such quality and process development goals can have significant time and resource requirements. The present work evaluates potential for using combined modelling and experimental approach, which may reduce this burden by predicting the properties of multicomponent tablets from pure component compression and compaction model parameters. Additionally, it evaluates the use of extrapolation from binary tablet data to determine theoretical pure component model parameters for materials that cannot be compacted in the pure form. It was found that extrapolation using binary tablet data - where one known component can be compacted in pure form and the other is a challenging material which cannot be - is possible. Various mixing rules have been evaluated to assess which are suitable for multicomponent tablet property prediction, and in the present work linear averaging using pre-compression volume fractions has been found to be the most suitable for compression model parameters, while for compaction it has been found that averaging using a power law equation form produced the best agreement with experimental data. Different approaches for estimating component volume fractions have also been evaluated, and using estimations based on theoretical relative rates of compression of the pure components has been found to perform slightly better than using constant volume fractions (that assume a fully compressed mixture). The approach presented in this work (extrapolation of, where necessary, binary tablet data combined with mixing rules using volume fractions) provides a framework and path for predictions for multicomponent tablets without the need for any additional fitting based on the multicomponent formulation composition. It allows the knowledge space of the tablet to be rapidly evaluated, and key regions of interest to be identified for follow-up, targeted experiments that that could lead to an establishment of a design and control space and forgo a laborious initial Design-of-Experiments.

Small-Scale Continuous Drug Product Manufacturing using Dropwise Additive Manufacturing and Three Phase Settling for Integration with Upstream Drug Substance Production

The pharmaceutical industry has traditionally relied on mass manufacturing to make its products. This has created multiple problems in the drug supply network, including long production times, inflexible and sluggish manufacturing and lack of personalized dosing. The industry is gradually adapting to these challenges and is developing novel technologies to address them. Continuous manufacturing and 3D printing are two promising techniques that can revolutionize pharmaceutical manufacturing. However, most research studies into these methods tend to treat them separately. This study seeks to develop a new processing route to continuously integrate a 3D printing platform (Drop-on-Demand, DoD, printing) with crystallization that is generally the final step of the active ingredient manufacturing. Accomplishing this integration would enable harnessing the benefits of each method- personalized dosing of 3D printing and flexibility and speed of continuous manufacturing. A novel unit operation, three-phase settling (TPS), is developed to integrate DoD with the upstream crystallizer. To ensure on-spec production of each printed dosage, two process analytical technology tools are incorporated in the printer to monitor drug loading in manufactured drug products in real time. Experimental demonstration of this system is carried out via two case studies: the first study uses an active ingredient celecoxib to test the standalone operation of TPS; the second study demonstrates the operation of the integrated system (crystallizer - TPS - DoD) to continuously make drug products for the active ingredient- lomustine. A dissolution test is also performed on the manufactured and commercial lomustine drug products to compare their dissolution behavior.

Real-Time Monitoring of Critical Quality Attributes during High-Shear Wet Granulation Process by Near-Infrared Spectroscopy Effect of Water Addition and Stirring Speed on Pharmaceutical Properties of the Granules

To produce high-quality pharmaceuticals, a real-time monitoring method for the high-shear wet granulation process (HSWG) was developed based on near-infrared spectroscopy (NIRS). Samples consisting of lactose, potato starch, and hydroxypropyl cellulose were prepared using HSWG with varying amounts of purified water (80, 90, and 100 mL) and impeller speed (200, 400, and 600 rpm), which produces granules of different characteristics. Twelve batches of samples were used for the calibration and nine batches were used for validation. After drying, the median particle size (D50), tapped density (TD), and Hauser ratio (HR) were measured. The best calibration models to predict moisture content (MC), D50, TD, and HR were determined based on pretreated NIR spectra using partial least squares regression analysis (PLSR). The temporal changes in the pharmaceutical properties under different amounts of water added and stirring speed were monitored in real time using NIRS/PLSR. Because the most important critical quality attribute (CQA) in the process was MC, granule characteristics such as D50, TD, and HR were analyzed with respect to MC. They might be used as robust and simple monitoring methods based on MC to evaluate the pharmaceutical properties of HSWG granules.

Control strategy definition for a drug product continuous wet granulation process: Industrial case study

This paper describes the specific control strategy of the commercial manufacturing process of an immediate release tablet formulation based on continuous twin-screw wet granulation. This control strategy has been defined by a multidisciplinary team using an enhanced approach, in alignment with the quality by design principles. During process development, experiments have been performed according to multivariate designs first to identify critical material attributes and critical process parameters and then, to define process conditions generating a product having the required quality. Hence, controls have been applied on critical quality attributes and on related critical process parameters and critical material attributes. Due to the specificity of the process that combines batch and continuous unit operations, a specific control strategy has been designed to ensure intermediate and end product quality. Therefore, controls including soft sensor model and in process controls have been developed to continuously monitor granules residual moisture content, assay and dissolution as granules and tablets critical attributes. In addition, process analytical technology implementation enabled increased process understanding and provided support for the development of the control strategy. This study is therefore considered as a real industrial case study of control strategy definition and implementation for an intended commercial continuous manufacturing process.

A Multivariate Formulation and Process Development Platform for Direct Compression

The efficient development of robust tableting processes is challenging due to the lack of mechanistic understanding on the impact of raw material properties and process parameters on tablet quality. The experimental determination of the effect of process and formulation parameters on tablet properties and subsequent optimization is labor-intensive, expensive and time-consuming. The combined use of an extensive raw material property database, process simulation tools and multivariate modeling allows more efficient and more optimized development of the direct compression (DC) process. In this study, key material attributes and in-process mechanical properties with a potential effect on tablet processability and tablet properties were identified. In a first step, an extensive characterization of 55 raw materials (over 100 material descriptors) (Van Snick et al., 2018) and 26 formulation blends (31 material descriptors) (Dhondt et al., 2022) was performed. These blends were subsequently compacted on a compaction simulator under multiple process conditions through a design of experiments (DoE) approach. A T-shaped partial least squares (T-PLS) model was established which correlates tablet quality attributes with process settings, raw material properties and blend ratios. During future development of the DC formulation and process for a new active pharmaceutical ingredient (API), this model can then be used to provide a preliminary formulation and compaction process settings as starting point to be further optimized during development trials based on well-defined raw material characteristics and compaction tests. This study hence contributes to a better understanding on the impact of raw material properties and process settings on a DC process and final properties of the produced tablets; and provides a platform allowing a more efficient and more optimized development of a robust tableting process.

Increasing the Batch Size of a QESD Crystallization by Using a MSMPR Crystallizer

Quasi-emulsion solvent diffusion (QESD) crystallizations can improve the micromeritic properties of drugs and excipients. A solution is dispersed in a miscible antisolvent as a transient emulsion. Using this technique, substances that normally crystallize in the form of e.g., needles, agglomerate into spherical, hollow particles. A disadvantage of QESD crystallizations is that the particle size of the agglomerates decreases with an increased solvent fraction of the mother liquor. Therefore, in batch production, many consecutive runs have to be performed, which is a time- and material-intensive process. The aim of this study was to convert a previously used lab-scale batch crystallizer into a mixed-suspension, mixed-product removal (MSMPR) crystallizer, since the batch size could be simply increased by increasing the run time of the system. The mean residence time (MRT) and solvent fraction in the system was predicted and verified using actual measurement curves. The experiments showed that >50 g QESD metformin hydrochloride could be crystallized in a single run, without observing a large shift in the particle size, while maintaining good flowability. Observations regarding the effect of the MRT on the particle size distribution could be verified for the production on a larger scale than previously described.

Stabilizing vaccines via drying: Quality by design considerations

Pandemics and epidemics are continually challenging human beings' health and imposing major stresses on the societies particularly over the last few decades, when their frequency has increased significantly. Protecting humans from multiple diseases is best achieved through vaccination. However, vaccines thermal instability has always been a hurdle in their widespread application, especially in less developed countries. Furthermore, insufficient vaccine processing capacity is also a major challenge for global vaccination programs. Continuous drying of vaccine formulations is one of the potential solutions to these challenges. This review highlights the challenges on implementing the continuous drying techniques for drying vaccines. The conventional drying methods, emerging technologies and their adaptation by biopharmaceutical industry are investigated considering the patented technologies for drying of vaccines. Moreover, the current progress in applying Quality by Design (QbD) in each of the drying techniques considering the critical quality attributes (CQAs), critical process parameters (CPPs) are comprehensively reviewed. An expert advice is presented on the required actions to be taken within the biopharmaceutical industry to move towards continuous stabilization of vaccines in the realm of QbD.

Design and Optimization of the Single-Stage Continuous Mixed Suspension-Mixed Product Removal Crystallization of 2-Chloro-N-(4-methylphenyl)propenamide

A continuously operated single-stage mixed suspension-mixed product removal (MSMPR) crystallizer was developed for the continuous cooling crystallization of 2-chloro-N-(4-methylphenyl)propanamide (CNMP) in toluene from 25 to 0 °C. The conversion of the previous batch to a continuous process was key to developing a methodology linking the synthesis and purification unit operations of CNMP and gave further insight in the development of continuous process trains for active pharmaceutical ingredient materials. By monitoring how parameters such as cooling and agitation rates influence particle size and the yield, two batch start-up strategies were compared. The second part of the study focused on developing and optimizing the continuous cooling crystallization of CNMP in the MSMPR crystallizer in relation to the yield by determining the effects of varying the residence time and the agitation rates. During the MSMPR operation, the plot of the focused beam reflectance measurement total counts versus time oscillates and reaches an unusual state of control. Despite the oscillations, the dissolved concentration was constant. The yield and production rate from the system were constant after two residence times, as supported by FTIR data. The overall productivity was higher at shorter residence times (τ), and a productivity of 69.51 g/h for τ = 20 min was achieved for the isolation of CNMP.

Binary Solvent Swap Processing in a Bubble Column in Batch and Continuous Modes

A lab-scale bubble column was investigated as an alternative means to achieve a low-temperature binary solvent swap of solutions containing pharmaceutical materials at atmospheric pressure, for batch and continuous configurations. The rate of solvent evaporation was predicted by first-principles vapor–liquid equilibrium (VLE) thermodynamic modeling and compared to experimentally achieved results. For batch configurations, evaporation rates of up to 5 g/min were achieved at gas flow rates up to 2.5 L/min (0.21 m/s superficial velocity) and temperatures up to 50 °C. This achieved 99 mol % purity of the desired solvent within three “put and take” evaporations from a 50:50 starting mixture. The evaporation rate profiles for the duration of the experiments were calculated, and the changing concentration profile was predicted within satisfactory error margins of <5%. Continuous process modeling explored a multistage equilibrium configuration and could predict the approach to attaining steady-state operation for various operating conditions. All rates of evaporation and resulting changes in solution concentration were measured, and direct comparison of model predictions fell within instrumentation error margins, as previously. This underlined the capability of the model to provide accurate representations of predicted evaporation rates and binary solution concentration changes during operation.