Steroidal antiandrogen
A steroidal antiandrogen (SAA) is an antiandrogen with a steroidal chemical structure. They are typically antagonists of the androgen receptor (AR) and act both by blocking the effects of androgens like testosterone and dihydrotestosterone (DHT) and by suppressing gonadal androgen production. SAAs lower concentrations of testosterone through simulation of the negative feedback inhibition of the hypothalamus. SAAs are used in the treatment of androgen-dependent conditions in men and women, and are also used in veterinary medicine for the same purpose. They are the converse of nonsteroidal antiandrogens (NSAAs), which are antiandrogens that are not steroids and are  structurally unrelated to testosterone. Medical uses. SAAs are used in clinical medicine for the following indications: Pharmacology. Unlike NSAAs, most SAAs show off-target hormonal activity such as progestogenic, glucocorticoid, or antimineralocorticoid activity, possess antigonadotropic effects, and are weak partial agonists of the AR with some capacity to activate the receptor. Due to their antigonadotropic effects, SAAs lower androgen levels in addition to directly blocking the actions of androgens at the AR; at sufficiently high dosages, they are able to lower circulating testosterone levels by up to 70 to 80% in men, to just above the castrate range. However, due  to their other hormonal effects, suppression of estrogen levels alongside testosterone levels, and AR activation, SAAs have increased side effects and show lower efficacy in the treatment of prostate cancer relative to NSAAs. List of SAAs. Marketed. Miscellaneous. Steroidal androgen synthesis inhibitors like the CYP17A1 inhibitor abiraterone acetate (Zytiga) or the 5α-reductase inhibitors finasteride and dutasteride could also technically be described as "SAAs", but the term is usually reserved to describe AR antagonists (and sometimes progestogenic antigonadotropins).