Chapter 5: Route Design and Selection

Process chemists in the pharmaceutical industry are responsible for designing an efficient synthetic route for the manufacture of an active pharmaceutical ingredient (API). The design of synthetic routes typically follows a plan–do–review cycle. The degree of success in working through this cycle depends upon four key capabilities: (1) responding to the needs of the drug development programme, (2) criteria for route evaluation and selection, (3) generation and prioritisation of ideas for route design and (4) maximising the value of experimental work. Criteria for route evaluation and selection involve factors associated with safety, environmental, legal, economics, control and throughput (SELECT). These factors are illustrated using examples from drug development programmes from different pharmaceutical companies. The final aim of a route design project is to identify and select a suitable synthetic route for API manufacture.