George Bryson

The Pharmacodynamics and Toxicology of Steroids and Related Compounds

Publisher Summary The steroid hormones are cyclopenta[a]phenanthrene derivatives. Because hormones by definition function at a target site removed from the site of origin, transport mechanisms for and their different affinities for natural or synthetic steroids contribute to the physiologic response. The origin of the natural steroid and the fate of it and its synthetic analogs are governed by endogenous enzyme systems. The role of the steroid at the receptor site, whether it is physical, resulting from secondary valence effects, or by chemical reactivity, is considered. This chapter discusses the synthetics or natural products that do not have the exact steroid carbon-ring skeleton if they produce physiologic effects akin to those of natural steroids by virtue of required spatial configurations and similar active functional groups. Measurement of steroids in early research relied upon the biologic assay, which remains a final arbiter when different methodological approaches yield different reported values.