Used primarily as a reference standard in pharmaceutical research and quality control, 11-Keto Budesonide is a major metabolite of the corticosteroid budesonide. It plays a critical role in metabolic studies aimed at understanding the biotransformation and pharmacokinetics of budesonide in the human body. Due to its structural similarity to budesonide, it is often analyzed in biological samples such as plasma, urine, and feces to assess drug metabolism and clearance rates. It is also employed in the development and validation of analytical methods like liquid chromatography-mass spectrometry (LC-MS) for accurate detection of budesonide metabolites. Its presence in metabolic pathways helps researchers evaluate the efficacy and safety profile of budesonide-based therapies used in treating inflammatory conditions such as asthma and Crohn’s disease.