The forced degradation study is considered a vital analytical aspect of the drug development program for small molecules. Forced degradation, commonly known as stress testing, is carried out to demonstrate as specificity to developed a stability-indicating analytical method, using high pressure liquid chromatography (HPLC), i.e., a single analytic method that is capable of separating the degradant peaks from the drug substance/drug product peak. As per International Conference on Harmonization (ICH) guidelines (Q1A), stability studies need to be performed to propose the shelf life of new drug substances and/or drug products. Shelf life studies are part of various regulatory submissions to the FDA.
DOE is a very powerful tool that can be used to characterize a process. This article discusses several types of experiments, as well as the basic statistical tools and techniques, that can be used when performing a DOE.