An active pharmaceutical ingredient (API) is purified by fractional batch distillation to achieve a high purity drug substance. This work is to improve the process throughput and to increase the yield using batch distillation modeling and engineering principles to better understand the process so high quality product can be produced consistently A batch of the drug substance was produced in about 7 days by batch distillation using a packed column with approximately 32 theoretical plates Process improvements were required to decrease the cycle time. Based on process modeling and other engineering principles, four process improvements have been made to increase the manufacture throughput After improvements the average cycle time has been reduced to 25 days from an average of 7 days process originally Furthermore, the yield is also increased This was achieved with the original equipment Since the changes are within the regulatory filings for the process, they are implemented quickly in commercial production. (C) 2010 Elsevier Ltd All rights reserved