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 Consequently, pharmaceutical companies are transitioning away from outdated batch lines, in large part motivated by the many advantages of continuous manufacturing (e.g., low cost, quality assurance, shortened lead time).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.

Reactive crystallization: a review

Reactive crystallization is not new, but there has been recent growth in its use as a means of improving performance and sustainability of industrial processes.

An Overview of Drug Substance Manufacturing Processes

To develop a comprehensive understanding of pharmaceutical drug substance manufacturing (DSM) processes, we conducted a data mining study to examine 50 new drug applications (NDAs) approved in 2010-2016. We analyzed the prevalence of several frequently deployed in-process control (IPC) techniques and postreaction workup procedures, as well as the operational conditions specified for reactions and workups. Our findings show that crystallization and high-performance liquid chromatography (HPLC) were the most commonly used workup steps and in-process controls, respectively, in drug substance manufacturing. On average, each NDA implemented 12.6 in-process controls and 11.3 workups. Operation time for reactions and workup procedures varied from a few minutes to multiple days, though 61% of these were between 1 and 10 h.

An automated modular assembly line for drugs in a miniaturized plant

We report here a fully automated, end-to-end, integrated continuous manufacturing process for a small-molecule generic medication with built-in quality assurance. The entire process fits into a box of 30.7 m2 modular footprint and a total residence time of less than 30 h, with a throughput up to 40.3 × 106 tablets per year.

Continuous reactive crystallization of an API in PFR-CSTR cascade with in-line PATs

The influence of PFR on crystal size distribution, reaction and crystallization yields, and supersaturation level was investigated.

An experimental study on polymorph control and continuous heterogeneous crystallization of carbamazepine

Influences of superstaturation, stirring, anti-solvent, and polymer type on polymorph are investigated.