Small-Volume Continuous Manufacturing of Merestinib. Part 2. Technology Transfer and cGMP Manufacturing

Flow fermentation: microsystems for whole-cell bioproduction processes

Industrial biotechnology utilizes whole cells for the production of value-added goods in large-scale bioreactors. The miniaturization of bioreactors has greatly contributed to the understanding and optimization of bioprocesses. However, microsystems for the production of value-added goods have thus far only been established in chemistry and biocatalysis/biotransformation but are rarely applied for whole-cell bioprocesses. Here, we discuss the fundamental and translational aspects of how microsystems could be used as production units for future whole-cell bioproduction processes. The characteristics and resulting advantages of microsystems are introduced and current production approaches are highlighted. Finally, we provide perspectives on establishing future whole-cell bioproduction processes at the microscale, here introduced as flow fermentation. Flow fermentation potentially enables entirely new bioprocesses and application fields.

Evaluation of a compact composite sensor array for concentration monitoring of solutions and suspensions via multivariate analysis

Compact composite probes were identified as a priority to alleviate space constraints in miniaturized unit operations and pharmaceutical manufacturing platforms. Therefore, in this proof of principle study, a compact composite sensor array (CCSA) combining ultraviolet and near infrared features at four different wavelengths (280, 340, 600, 860 nm) in a 380 × 30 mm housing (length x diameter, 7 mm diameter at the probe head), was evaluated for its capabilities to monitor in situ concentration of solutions and suspensions via multivariate analysis using partial least squares (PLS) regression models. Four model active pharmaceutical ingredients (APIs): warfarin sodium isopropanol solvate (WS), lidocaine hydrochloride monohydrate (LID), 6-mercaptopurine monohydrate (6-MP), and acetaminophen (ACM) in their aqueous solution and suspension formulation were used for the assessment. The results demonstrate that PLS models can be applied for the CCSA prototype to measure the API concentrations with similar accuracy (validation samples within the United States Pharmacopeia (USP) limits), compared to univariate CCSA models and multivariate models for an established Raman spectrometer. Specifically, the multivariate CCSA models applied to the suspensions of 6-MP and ACM demonstrate improved accuracy of 63% and 31%, respectively, compared to the univariate CCSA models [1]. On the other hand, the PLS models for the solutions WS and LID showed a reduced accuracy compared to the univariate models [1].

Fischer indole synthesis in DMSO/AcOH/H2O under continuous flow conditions

A new continuous flow synthetic method for preparing indole and its derivatives are successfully developed to overcome the disadvantages of traditional batch methods, such as low conversion rates, long reaction times, and amplification effects. The method represents a sustainable and efficient preparation of indole and its derivatives without the need for additional catalysts. By investigating the effects of the reaction temperature, the solvent, the equivalence ratio, and the residence time, high conversion rates and excellent yields were simultaneously achieved within 20 min under optimized conditions. For the template reaction, DMSO/H2O/AcOH = 2:1:1 is used as the solvent, the reaction temperature is 110 °C, and the ratio of phenylhydrazine hydrochloride to cyclopentanone is 1:1.05. Indole and a wide array of its derivatives are synthesized to verify the universality of the method, and most of the reactions exhibit satisfactory conversion rates and high yields are obtained. This new continuous flow method is more suitable for industrial scale-up relative to traditional batch methods.

Impurity incorporation in solution crystallization: diagnosis, prevention, and control

This work highlights recent advances in the diagnosis, prevention, and control of impurity incorporation during solution crystallization.

Continuous stirred-tank reactor cascade platform for self-optimization of reactions involving solids

Research-scale fully automated flow platform for reaction self-optimization with solids handling facilitates identification of optimal conditions for continuous manufacturing of pharmaceuticals while reducing amounts of raw materials consumed.

Real-time concentration monitoring using a compact composite sensor array for in situ quality control of aqueous formulations

Recent advancements have demonstrated the feasibility of refrigerator-sized pharmaceutical manufacturing platforms (PMPs) for integrated end-to-end manufacturing of active pharmaceutical ingredients (APIs) into formulated drug products. Unlike typical laboratory- or industrial-scale setups, PMPs present unique requirements for process analytical technology (PAT) with respect to versatility, flexibility, and physical size to fit into the PMP space constraints. In this proof of principle study, a novel compact composite sensor array (CCSA) combining ultraviolet (UV) and near infrared (NIR) features at four different wavelengths (280, 340, 600, 860 nm) with temperature measuring capability in a 380 × 30 mm housing (length x diameter, 7 mm diameter at the probe head), were evaluated. The results indicate that the CCSA prototype is capable of measuring the solution and suspension concentrations in aqueous formulations of four model APIs (warfarin sodium isopropanol solvate, lidocaine hydrochloride monohydrate, 6-mercaptopurine monohydrate, acetaminophen) in situ and in real-time with similar accuracy as an established Raman spectrometer commonly applied for method development.

Continuous Flow Synthesis of Anticancer Drugs

Continuous flow chemistry is by now an established and valued synthesis technology regularly exploited in academic and industrial laboratories to bring about the improved preparation of a variety of molecular structures. Benefits such as better heat and mass transfer, improved process control and safety, a small equipment footprint, as well as the ability to integrate in-line analysis and purification tools into telescoped sequences are often cited when comparing flow to analogous batch processes. In this short review, the latest developments regarding the exploitation of continuous flow protocols towards the synthesis of anticancer drugs are evaluated. Our efforts focus predominately on the period of 2016-2021 and highlight key case studies where either the final active pharmaceutical ingredient (API) or its building blocks were produced continuously. It is hoped that this manuscript will serve as a useful synopsis showcasing the impact of continuous flow chemistry towards the generation of important anticancer drugs.

Reactor design and selection for effective continuous manufacturing of pharmaceuticals

Pharmaceutical production remains one of the last industries that predominantly uses batch processes, which are inefficient and can cause drug shortages due to the long lead times or quality defects. Consequently, pharmaceutical companies are transitioning away from outdated batch lines, in large part motivated by the many advantages of continuous manufacturing (e.g., low cost, quality assurance, shortened lead time). As chemical reactions are fundamental to any drug production process, the selection of reactor and its design are critical to enhanced performance such as improved selectivity and yield. In this article, relevant theories, and models, as well as their required input data are summarized to assist the reader in these tasks, focusing on continuous reactions. Selected examples that describe the application of plug flow reactors (PFRs) and continuous-stirred tank reactors (CSTRs)-in-series within the pharmaceutical industry are provided. Process analytical technologies (PATs), which are important tools that provide real-time in-line continuous monitoring of reactions, are recommended to be considered during the reactor design process (e.g., port design for the PAT probe). Finally, other important points, such as density change caused by thermal expansion or solid precipitation, clogging/fouling, and scaling-up, are discussed.

Graphical abstract

Design Space Identification and Visualization for Continuous Pharmaceutical Manufacturing

Progress in continuous flow chemistry over the past two decades has facilitated significant developments in the flow synthesis of a wide variety of Active Pharmaceutical Ingredients (APIs), the foundation of Continuous Pharmaceutical Manufacturing (CPM), which has gained interest for its potential to reduce material usage, energy and costs and the ability to access novel processing windows that would be otherwise hazardous if operated via traditional batch techniques. Design space investigation of manufacturing processes is a useful task in elucidating attainable regions of process performance and product quality attributes that can allow insight into process design and optimization prior to costly experimental campaigns and pilot plant studies. This study discusses recent demonstrations from the literature on design space investigation and visualization for continuous API production and highlights attainable regions of recoveries, material efficiencies, flowsheet complexity and cost components for upstream (reaction + separation) via modeling, simulation and nonlinear optimization, providing insight into optimal CPM operation.