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Heated bladed mixers are widely used to process granular materials. Yet, despite their ubiquity, unanswered questions remain regarding how heat transfer occurs in this system, particularly when scaling up the process. In this work, the discrete element method was coupled with a heat transfer model to investigate how the amount of material and the mixer size influence the particle bed heating time. The findings show that the relationship between the fill level and the heating time depends on the heating area of the mixer relative to the amount of material, the bed compression, and the mixing rate. The results also indicate that the heating time is directly proportional to the mixer diameter. The proportionality constant has an order of magnitude of one and depends on the impeller rotation rate. Overall, this work enhances fundamental understanding of the elements at play during the scale up of granular processes in heated bladed mixers.

The design of pharmaceutical crystallization processes is a challenging engineering problem because of the specific and versatile quality requirements of the end-product, amplified by the tight reg...

The objective of the research was to improve the process design of a combined antisolvent-cooling crystallization to reduce the degree of agglomeration of a real active pharmaceutical ingredient product, which was manufactured using a crystallization stage employing a methanol/water solvent system. Knowledge was gained from the use of process analytical technology (PAT) tools to monitor the process variables, allowing particle size, degree of agglomeration, solute concentration, and supersaturation to be tracked throughout the process. Based on knowledge of the solubility behavior and interpretation of the PAT histories, changes were made to the sequences of antisolvent addition and cooling within the crystallization process to reduce agglomeration in the final product. Different seed loadings and seeding addition points were also investigated to maintain operation within lower supersaturation regions of the phase diagram to limit agglomeration and avoid an undesired polymorphic transformation to an unstable form. The improved sequences of operations and seeding conditions did not provide sufficient improvement in the product quality and so were augmented by applying wet milling for further deagglomeration followed by temperature cycling to remove fine particles generated during milling. Open-loop heating and cooling cycles produced some limited improvements, whereas closed-loop direct nucleation control methods using FBRM as a feedback sensor for particle counts per second were much more successful at producing high-quality crystals of the desired polymorphic form. The work shows that understanding the trajectory of the process through the phase diagram to follow appropriate supersaturation profiles gives improved control of the various kinetic mechanisms and can be used to improve the quality of the final product.

This study compares the use of wet milling and indirect ultrasound for promoting nucleation and controlling the particle size during the continuous crystallization of a hard-to-nucleate active pharmaceutical ingredient (API). Both an immersion and an external wet mill installed on a recirculation loop were investigated. It was found that all methodologies significantly improved the nucleation kinetics, and the effects of key process parameters (e.g., mill speed, temperature, and ultrasound intensity) on particle size were experimentally investigated. A minimum d50 of 27 and 36.8 μm was achieved when using the wet mill and ultrasound, respectively. The effectiveness of wet milling was demonstrated in a three-stage mixed suspension mixed product removal continuous crystallization of the API that was operated continuously for 12 h (eight residence times), achieving a steady state with minimal fouling. Strategies for improving the overall robustness of the setup in routine manufacturing are discussed.

A material-sparing screening methodology has been developed for assessing the risk of particle size attrition of active pharmaceutical ingredients (APIs) during agitated drying using a single-ball ...

This work demonstrates a systematic development of a digital twin of a commercial active pharmaceutical ingredient (API) - Compound A - crystallization processes to be used for in-silico design of experiments (DoE) and process optimization. Eleven highly corelated kinetic parameters were estimated by exploiting an optimization approach with an evolutionary algorithm, to fit to concentration profile, mean size and the shape distribution of the product. Two more experiments were then performed to validate the model showing that the developed model could predict the product size and shape properties. The digital twin of the process was used to perform in silico design of experiments to understand the attainable operating space of the system and provide a framework for rapid quality-by-design (QbD). Subsequently the model was used in a dynamic optimization framework for the digital design of the API crystallization process to achieve the critical quality attributes (CQAs) without extensive experimentation.

A flow chemistry process for the synthesis of a key boronic acid starting material was developed utilizing flow flash chemistry that allowed formation and subsequent productive reaction of an unstable organolithium intermediate. Rapid scale-up from Discovery Chemistry and process optimization to kilogram-scale production was achieved using a short residence time (0.25 s) and noncryogenic temperature (0 °C), without the need to increase the number of reactors. A comparison of the flow process with a Miyaura borylation process suggested some potential benefit in the overall process operating efficiency from avoiding the use of Pd and genotoxic boron reagents.

The drying unit operation is used extensively in the pharmaceutical industry, but often a lack of understanding of the impact of the drying process parameters on active pharmaceutical ingredient critical quality attributes can create challenges during development. A working group within the Enabling Technologies Consortium identified common challenges in pharmaceutical drying development, including material constraints for scale-up studies and transferring to different equipment types and sizes. This manuscript surveys current practices within the industry for drying development related to chemical and physical stability, drying kinetics, and powder properties and highlights common development gaps for improving drying development workflows within the industry. The ultimate goal is to encourage further fundamental research and technological advancements for improving the drying development workflow.

The creation of the Enabling Technologies Consortium (ETC) is described. The ETC fosters precompetitive collaborations aimed at the development and evaluation of new enabling technologies for pharmaceutical research and development, with an initial focus on chemistry, manufacturing, and controls. An overview of the structure and function of the new organization, which will carry out its work while remaining mindful of antitrust compliance requirements, is herein presented along with a description of several ongoing development projects.

A revised Miyaura borylation process has been developed using tetrahydroxydiboron that avoids the use of bis(pinacolato) diboron and hence the need to hydrolyze the resulting boronic ester to its corresponding acid. The process was greatly simplified and successfully scaled-up in the pilot plant on a 65 kg scale, reducing plant cycle time and resulting in a 47% overall cost reduction. Furthermore, methodology for the study of the oxygen sensitivity of the process is reported that allowed for optimization of the amount of tetrahydroxydiboron and catalyst used. These studies also demonstrated an oxygen-induced decomposition of tetrahydroxydiboron.

A simple screening protocol has been developed for assessing the agglomeration potential of active pharmaceutical ingredients (APIs) using resonant acoustic mixing that minimizes the quantity of API used. This methodology improves upon existing ones as it allows for multiple conditions to be screened in parallel, saving time and allowing for the study of agglomeration and optimization of the drying unit operation to take place early in development. In addition to a qualitative (visual) assessment, quantitative data can be obtained after the material has been dried therefore accounting for a measure of cake hardening. This methodology was also extended to assess the friability of the generated agglomerates and was validated using a scaled-down agitated filter dryer (AFD). The impact of particle size, particle size distribution, solvent selection, and solvent loading on the agglomeration potential for a Takeda API is also discussed which allowed for the development of an improved drying process that was suc...

The work proposes a combination of model-free and model-based quality-by-control (mfQbC and mbQbC) paradigms as a general framework for the optimal crystallization design with the aim of minimization of fines and agglomerates in the product. This framework provides an improved alternative to the current industrial practice, by the combined use of feedback control and mathematical models for rapid design of robust crystallization processes. The implementation of the proposed mbQbC framework enhanced the prediction of crystallization events and was able to achieve better control of the crystallization processes by providing controlled heating/cooling cycles, for deagglomeration and fines destruction. The information for parameter estimation and optimization calculations was collected from the experiments in mfQbC part, which additionally also provided a rapid design of robust operating conditions, which subsequently in the mbQbC approach were improved to achieve optimal operation.

Alisertib sodium, an investigational oral oncology drug, posed some challenges toward developing a robust and scalable drying process employing an agitated filter dryer that manifested themselves during the technical transfer to a new manufacturing site. The API studied was a monohydrate that was found to readily dehydrate and agglomerate, impacting both drug product (DP) manufacture and in vitro dissolution. A scale down agitated filter dryer was designed that was used to study the drying unit operation and identify key process parameters. Through a combination of lab- and pilot plant-scale experiments, suitable drying conditions were developed that minimized agglomeration, eliminated dehydration, and produced API that behaved acceptably in downstream DP manufacture.

Continuous-flow solution crystallization is an approach to manufacture pharmaceutical crystals with improved control of product characteristics, simplified postcrystallization operations, higher production rate flexibility, and reduced capital costs and footprint. An indirect ultrasonication-assisted nucleation process is designed to vary the seed generation rate during operation independent of mass flow rate, by varying the ultrasonication power. The ultrasonication probe is pressed against a tube to generate a spatially localized zone within the tube inside of a temperature bath for the generation of crystal nuclei without heating or contaminating the supersaturated solution. This nucleation design is integrated into a continuous slug-flow crystallization process to generate uniform-sized product crystals within each slug at a high supersaturation level and a short residence time of ∼8.5 min, without inducing significant secondary nucleation. By increasing size uniformity, the indirect ultrasonication-a...

A modeling-based strategy is disclosed for identifying reaction conditions for the safe and effective scale-up of highly energetic hydrogenation reactions. The model was developed within Scale-up Systems’s DynoChem 2011 and takes under consideration the kinetics of the reaction, the reactor heat transfer capabilities, and the degree of mass transfer. Fourier transform infrared spectroscopy (FT-IR), heat flow, and H2 uptake data were used to determine the reaction kinetics that were found to be most accurately described by a Langmuir–Hinshelwood type model. The scale-up model was validated within our kilo-laboratory using a 5 L reactor.

A novel continuous crystallizer design is described with the potential to provide improved control of crystal properties, improved process reproducibility, and reduced scale-up risk. Liquid and gas are introduced into one end of the tube at flow rates selected to spontaneously generate alternating slugs of liquid and gas that remain stable while cooling crystallization occurs in each liquid slug. Mixing within each stable self-circulating slug is maximized by controlling the slug aspect ratio through specification of liquid and gas flow rates. The crystallizer is designed so that nucleation and growth processes are decoupled to enhance the individual control of each phenomenon. Coaxial or radial mixers combine liquid streams to generate seed crystals immediately upstream of the growth zone where nucleation is minimized, and crystal growth is controlled by the varying temperature profile along the length of the tube. The slug-flow crystallizer design is experimentally demonstrated to generate large uniform...

Sanglifehrin A (SFA) is a novel immunosuppressive natural product isolated from Streptomyces sp. A92-308110. SFA has a very strong affinity for cyclophilin A (IC(50) = 6.9 +/- 0.9 nM) but is structurally different from cyclosporin A (CsA) and exerts its immunosuppressive activity via a novel mechanism. SFA has a complex molecular structure consisting of a 22-membered macrocycle, bearing in position 23 a nine-carbon tether terminated by a highly substituted spirobicyclic moiety. Selective oxidative cleavage of the C(26)=C(27) exocyclic double bond affords the spirolactam containing fragment 1 and macrolide 2. The affinity of 2 for cyclophilin (IC(50) = 29 +/- 2.1 nM) is essentially identical to SFA, which indicates that the interaction between SFA and cyclophilin A is mediated exclusively by the macrocyclic portion of the molecule. This observation was confirmed by the X-ray crystal structure resolved at 2.1 A of cyclophilin A complexed to macrolide 16, a close analogue of 2. The X-ray crystal structure showed that macrolide 16 binds to the same deep hydrophobic pocket of cyclophilin A as CsA. Additional valuable details of the structure-activity relationship were obtained by two different chemical approaches: (1) degradation work on macrolide 2 or (2) synthesis of a library of macrolide analogues using the ring-closing metathesis reaction as the key step. Altogether, it appears that the complex macrocyclic fragment of SFA is a highly optimized combination of multiple functionalities including an (E,E)-diene, a short polypropionate fragment, and an unusual tripeptide unit, which together provide an extremely strong affinity for cyclophilin A.

The total syntheses of 2,2‘-epi-cytoskyrin A, rugulosin, and the alleged structure of rugulin are described. These naturally occurring bisanthraquinones and their relatives are characterized by novel molecular architectures at the core, at which lies a more or less complete, cage-like structural motif termed “skyrane”. The strategies developed for their total synthesis feature a cascade sequence called the “cytoskyrin cascade” and deliver these molecules in short order and in a stereoselective manner.