ABSTRACT
Glucocorticoids evoke many biological responses in the human body. Consequently, pharmacologists have long dreamed of constructing from modular features a steroid with precisely defined and highly specific biological activity. Initially it seemed logical that there should be a straightforward relationship between steroid structure and biological activity. The chapter discusses the evidence and possible causes for variations both in the amount of agonist activity displayed by antiglucocorticoids and in the potency of glucocorticoids. A direct relationship has been established between the affinity of glucocorticoids binding to the receptor and the potency of each steroid as an agonist. Unfortunately no such correlation has evolved for antiglucocorticoids. The maximal response to saturating levels of glucocorticoids, and probably all steroids, is determined by the amount of receptor available. However, there is mounting evidence that the amount of induction seen with subsaturating concentrations of glucocorticoids is influenced by other factors.
