SB 204990 is a potent and selective inhibitor of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), an enzyme involved in the regulation of active glucocorticoid levels in tissues. It is primarily used in research settings to study the role of glucocorticoids in metabolic pathways, particularly in adipose tissue, liver, and other key organs. Researchers employ SB 204990 to investigate its effects on cortisol production, insulin sensitivity, lipid metabolism, and glucose homeostasis, with applications in understanding and targeting metabolic disorders such as obesity, type 2 diabetes, and metabolic syndrome. While it has been explored in contexts like inflammation and certain cancers due to glucocorticoid involvement, its main utility lies in metabolic research and potential therapeutic development.