Hormones, Sex Hormones

Abstract

Progestins are a class of steroids named for their role in maintaining pregnancy. Naturally occurring progestins, such as progesterone, are 21‐carbon steroids having the basic pregnane structure. Synthetic progestins are derived from four structural groups; ie, 5α‐prenanes, 5α‐androstanes, estranes, and gonanes. They are produced by chemical and microbial degradation of naturally occurring steroids and by total synthesis. Structure–activity relationships of progestins have been explored using computer‐aided techniques. The principal use of progestins is in contraception, prescribed alone or in combination with estrogens, where they act primarily to prevent uncontrolled estrogen stimulation of the uterine endometrium. Progestins have other uses based on their antiestrogenic effects. They are known to cause a conformational change in receptors. When bound to an agonist, progestin receptors act as transcription factors, altering the rate of expression of various genes. New antiprogestins with improved receptor specificity are becoming available and may eventually be used in some of the same therapeutic areas as progestin agonists.