@article {Lamerzpdajpst.2021.012662, author = {Jens Lamerz and Oana Mihaela Danila and Andreas Schuster and Janine Burren and Christian Moessner and Wolfgang G{\"o}hring and Pankaj Rege and Helmut Stahr and Stefan Hildbrand and Daniel Coleman}, title = {An Improved Impact Ratio for Identifying Critical Process Parameters in Pharmaceutical Manufacturing Processes}, elocation-id = {pdajpst.2021.012662}, year = {2022}, doi = {10.5731/pdajpst.2021.012662}, publisher = {Parenteral Drug Association (PDA)}, abstract = {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. When 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 paper 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.}, issn = {1079-7440}, URL = {https://journal.pda.org/content/early/2022/07/15/pdajpst.2021.012662}, eprint = {https://journal.pda.org/content/early/2022/07/15/pdajpst.2021.012662.full.pdf}, journal = {PDA Journal of Pharmaceutical Science and Technology} }