Medicines are one of the few remaining products still produced in batches, but switching to continuous processing can speed production, save costs and increase flexibility, according to Eli Lilly.

By next year, Lilly will have installed and demonstrated four different continuous-processing platforms, says Bret Huff, the firm’s vice president of small molecule design and development.

“Currently, almost all of our potential medicines that are in development have continuous-processing steps in place,” he added, speaking at the national meeting of the American Chemical Society (ACS) in Indianapolis.

The production process still generally used by drugmakers involves a batch of ingredients undergoing a series of batch-wise reactions with isolation of solid intermediates before finally being isolated and drummed into bulk containers, the conference heard. The active pharmaceutical ingredient then moves on to the next step, processing into a granular form, followed by collection into bulk containers. The processing continues through drying and other stages before being compressed into tablets and coated.

However, Dr Huff pointed out, small amounts of the ingredients are inevitably lost and wasted at each step. Other inefficiencies take 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.

Drugmakers have continued to use traditional production methods for a number of reasons, Dr Huff told the meeting. In the past, for example, the technology did not exist to continuously produce drugs along a production line to ensure quality and purity. Also, companies lacked experience with continuous processing and faced the capital costs of redesigning production lines.

However, the US Food and Drug Administration (FDA) has been assuring them that there are no scientific, regulatory or other hurdles to adopting continuous processing, he said. And the process has many benefits, including reduced costs of making medicines, faster production and greater flexibility to tailor output to demand.

Doubling the number of tablets produced in a batch process, for example, would typically require doubling the amount of production equipment. In contrast, continuous production offers the flexibility to increase output to meet demand, he said.