Medicine of the 21st century is getting a hand from an idea Henry Ford had in the 19th century and implemented in 1908 - the concept of continuous mass production.

Billions of tablets, capsules and other forms of medicine that people take each year are still made made batch-wise.   A batch of ingredients typically undergoes a series of batch-wise reactions with isolation of solid intermediates before finally being isolated and drummed into bulk containers. The active pharmaceutical ingredient then moves on to the next step, processing into a granular form, followed by collecting into bulk containers. The processing continues through drying and other stages before being compressed into tablets and coated.

Bret E. Huff, Ph.D., with Eli Lilly and Company said in his keynote talk at the meeting of the American Chemical Society that the pharmaceutical industry has continued to use traditional production methods for a number of reasons. In the past, the technology did not exist to continuously produce drugs along a production line to ensure quality and purity. Then pharmaceutical companies lacked experience with continuous processing and faced the capital costs of redesigning production lines. 

But the U.S. Food and Drug Administration has been assuring companies that there are no scientific, regulatory or other hurdles to adopting continuous processing. And the approach has many benefits, including reduced costs of making medicines, faster production and greater flexibility to tailor production to demand. 

"The difference between batch and continuous processing is somewhat like the difference between a ferry boat and a bridge for getting cars and people across a river," explained Huff. "A ferry moves cars across a river one batch at a time. A bridge provides a continuous flow of cars across the river. A bridge is typically open, with the flexibility to meet demand, without having a line-up of cars waiting for the next trip across." 

In this traditional approach for producing medicine, small amounts of the ingredients inevitably are lost and wasted at each step, with other inefficiencies taking their toll. And it may take days or weeks to finish each batch of medicine. In continuous processing, in contrast, the individual batch steps occur continuously, as the ingredients move through the production process in assembly-line fashion. Quality-control testing and other monitoring are not necessarily separate operations done at the end of production of each batch, but can be fully integrated into the continuous-flow operation.

Continuous processing is used in most other large-scale manufacturing such as food production, petroleum refinement and water treatment, Huff noted. Some industries use an extreme version. Blast furnaces that produce iron from iron ore, for instance, may operate non-stop or with only brief pauses for 8-10 years. The machines that produce window glass run continuously for up to 18 years.

Doubling the number of tablets produced in a batch process would typically require doubling the amount of production equipment. Continuous production, in contrast, typically offers the flexibility to increase output to meet demand. 

"By early next year, Eli Lilly and Company will have installed and demonstrated four different continuous-processing platforms," Huff said. "Currently, almost all of our potential medicines that are in development have continuous-processing steps in place."