Continuous manufacturing of beta-lactam antibiotics by enzymatic reactive crystallization
Mcdonald, Matthew Alexander
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The enzymatic production of beta-lactam antibiotics can be simplified by integrating the synthesis and separation of the antibiotic within a single vessel. In situ crystallization during the synthesis of beta-lactam antibiotics improves yields by protecting the antibiotic, an intermediate in the enzyme catalyzed reaction pathway, from degradation by the enzyme. The design of a continuous synthesis, crystallization, and isolation (CSCI) process follows naturally because the reaction and crystallization kinetics are already coupled in the batch process. Rather than individually design and size several unit operations for use in series, a single unit that performs several operations at once was developed. The benefits of continuous reactive crystallization include simplified process control, improved environmental sustainability, and increased process performance. Enzyme catalysis decreases process mass intensity and increases reaction selectivity compared to chemical routes to beta-lactams. Use of process analytical technology (PAT) enables real time monitoring of critical process parameters (CPPs) to ensure production of pharmaceutical quality material. The kinetics of the enzyme reactions and antibiotic crystallization were determined in batch for ampicillin and cephalexin. A model of reactive crystallization was built and used to determine the optimal process configuration for continuous production of amoxicillin and cephalexin. Finally, implementation of the continuous process in the lab was begun. This process will enable more sustainable production of beta-lactam antibiotics with potential for on-demand production, especially important in light of recent drug shortages due to the 2020 SARS-CoV-2 pandemic.