Averaging level control to reduce off-spec material in a continuous pharmaceutical pilot plant

The judicious use of buffering capacity is important in the development of future continuous pharmaceutical manufacturing processes. The potential benefits are investigated of using optimal-averaging level control for tanks that have buffering capacity for a section of a continuous pharmaceutical pilot plant involving two crystallizers, a combined filtration and washing stage and a buffer tank. A closed-loop dynamic model is utilized to represent the experimental operation, with the relevant model parameters and initial conditions estimated from experimental data that contained a significant disturbance and a change in setpoint of a concentration control loop. The performance of conventional proportional-integral (PI) level controllers is compared with optimal-averaging level controllers. The aim is to reduce the production of off-spec material in a tubular reactor by minimizing the variations in the outlet flow rate of its upstream buffer tank. The results show a distinct difference in behavior, with the optimal-averaging level controllers strongly outperforming the PI controllers. In general, the results stress the importance of dynamic process modeling for the design of future continuous pharmaceutical processes

Reconfiguration of a Continuous Flow Platform for Extended Operation: Application to a Cryogenic Fluorine-Directed <i>ortho</i>-Lithiation Reaction

A flow platform for preparing various aromatic scaffolds using a low-temperature fluorine-directed <i>ortho</i>-lithiation reaction has been successfully reconfigured to allow large-scale processing over extended reaction periods. During the course of this work several key factors have resulted in the development of new technology such as stainless steel y-piece fittings capable of hosting a thermocouple at the point of mixing which directly controls the power output of a cryogenic cooling device. These developments have enabled the continuous processing of an industrially relevant product, where adequate mixing, cooling, and exotherm control are important for successful operation. The configuration culminates in a large-scale campaign where the flow platform is utilised to process over 100 g of pure product over 7 h, in a yield of 80% after workup

Development of a multi-step synthesis and workup sequence for an integrated, continuous manufacturing process of a pharmaceutical

The development and operation of the synthesis and workup steps of a fully integrated, continuous manufacturing plant for synthesizing aliskiren, a small molecule pharmaceutical, are presented. The plant started with advanced intermediates, two synthetic steps away from the final active pharmaceutical ingredient, and ended with finished tablets. The entire process was run on several occasions, with the data presented herein corresponding to a 240 h run at a nominal throughput of 41 g h-1 of aliskiren. The first reaction was performed solvent-free in a molten condition at a high temperature, achieving high yields (90%) and avoiding solid handling and a long residence time (due to higher concentrations compared to dilute conditions when run at lower temperatures in a solvent). The resulting stream was worked-up inline using liquid-liquid extraction with membrane-based separators that were scaled-up from microfluidic designs. The second reaction involved a Boc deprotection, using aqueous HCl that was rapidly quenched with aqueous NaOH using an inline pH measurement to control NaOH addition. The reaction maintained high yields (90-95%) under closed-loop control despite process disturbances. © 2014 American Chemical Society

The application of a plant-wide control strategy for an integrated continuous pharmaceutical pilot plant.

Continuous manufacturing offers potential opportunities for the improved manufacturing of pharmaceutical products. A key challenge is the development of an appropriate control strategy. The experimental application of an automated control strategy is presented for an end-to-end continuous pharmaceutical pilot plant. The process starts from an advanced intermediate compound and finishes with the tablet formation steps. The focus of the experimental results is on the design and performance of the control loops needed to produce a slurry of an active pharmaceutical ingredient and a solvent with specified material properties. The results demonstrate that automated control can successfully keep critical material attributes close to the desired set points for a sustained period of operation. This work aims to contribute to the development of future continuous pharmaceutical processes by providing a realistic case study of automated control of an integrated, continuous, pharmaceutical pilot plant