Activated pharmaceutical ingredients produced by microreactors versus batch processes: A review

In the pharmaceutical industry, drug synthesis is usually carried out by batch method. However, in recent years, continuous methods, specifically microfluidics and microreactors, have attracted a great deal of attention due to advantages such as better mass and heat transfer, safety, selectivity, yield, and surface-to-volume ratio. Thus, in this review, different microreactor properties such as flow regime pattern, operating pressure, selectivity, safety, reaction phase, operating and control, materials, and cost are addressed and discussed. In addition, microreactor applications in the synthesis of chemicals and drugs, polymerization, nanoparticle synthesis, photochemical, biodiesel production, and catalytic microreactors are presented in detail. Furthermore, a comparison of the flow process of a pharmaceutical industry's microreactor and a batch reactor used for different APIs, intermediates, and lead compounds is presented. The results revealed that 50% of such reactions would show more promising results when carried out in a microreactor system, while only 44% of examined cases preferred such systems. Ultimately, these authors believe that the current review is very suitable for newcomers in pharmaceutical industry material production research who might be attracted to this new technology due to the elementary and basic microfluidics concepts discussed in the present manuscript.