Objectives To implement, and evaluate the use of, lean methods in highly congested areas of the pharmacy department such as the clean room. Through the use of lean tools such as value stream mapping, value-added and non-value-added activities can be classified.

Methods From January 2010 to December 2011, the workload in the clean room was assessed. During the first 6 months, data analysed were workflow, delay in elaboration, time needed from medical prescription to delivery to end user, and quantity and seasonality of the workload. After implementation of the lean methods, a new value stream map was generated, and metrics related to workflow were evaluated again.

Results Although the production of compounding sterile preparations was no bigger than the production of other preparations such as total parenteral nutrition and intravenous admixtures, it showed great variability depending on the workday (range −48.6% to 52.7%). In addition, when the value stream map was assessed, a lot of steps in the process showed low-quality performance (first time quality 56%) and delays. Also, workload and delays in elaboration showed good linear correlation (r=0.849). After the use of new methods and skipping unnecessary steps, the future state value stream map showed an improvement in quality (first time quality 95%) and more efficient work.

Conclusions Through lean thinking, more-sterile preparation was adopted and improvements in quality were reported. Lean techniques represent continuous enhancement during a process, focusing on reducing non-value-added steps. In spite of the lack of extensive research on lean methods in health system institutions, they should be considered when new pro-efficiency measurements are implemented.