%0 Journal Article %A Jens Lamerz %A Oana Mihaela Danila %A Andreas Schuster %A Janine Burren %A Christian Moessner %A Wolfgang Göhring %A Pankaj Rege %A Helmut Stahr %A Stefan Hildbrand %A Daniel Coleman %T An Improved Impact Ratio for Identifying Critical Process Parameters in Pharmaceutical Manufacturing Processes %D 2022 %R 10.5731/pdajpst.2021.012662 %J PDA Journal of Pharmaceutical Science and Technology %P 497-508 %V 76 %N 6 %X The identification of critical process parameters in biologics and small molecule process development is a key element of quality by design. The objectivity and consistency of procedures to identify critical process parameters can be improved with the use of impact ratios. Impact ratios quantify a process parameter’s practical effect on a critical quality attribute relative to the critical quality attribute’s acceptance limits. If the impact ratio is large, i.e., exceeds a predefined impact ratio threshold, the recommendation is to classify the process parameter as a critical process parameter. This article introduces an improved and mathematically well-defined impact ratio. Benefits of this impact ratio are a consistent interpretation for many scenarios commonly encountered in practice, high suitability to automation, and the possibility of standardizing on a single impact ratio definition for pharmaceutical manufacturing. %U https://journal.pda.org/content/pdajpst/76/6/497.full.pdf