According to ICH Guideline Q8 (FDA/ICH, May 2006), design space is defined as the multidimensional combination and interaction of input variables (e.g., material attributes) and process parameters that have been demonstrated to provide assurance of quality. Working within the design space is not considered as a change. Movement out of the design space is considered to be a change and would normally initiate a regulatory postapproval change process. Design space is proposed by the applicant and is subject to regulatory assessment and approval (ICH Q8).

In this presentation, I will share my experiences on reviewing several QbD applications, such as the design space for final products, for drug substance, and for analytical methods.