Concept

Steroidal antiandrogen

Résumé
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. SAAs are used in clinical medicine for the following indications: Prostate cancer in men Benign prostatic hyperplasia in men Androgen-dependent skin and hair conditions like acne, hirsutism, seborrhea, and pattern hair loss (androgenic alopecia) in women Hyperandrogenism, such as due to polycystic ovary syndrome or congenital adrenal hyperplasia, in women As a component of hormone therapy for transgender women Precocious puberty in boys Hypersexuality and paraphilias in men and sex offenders Priapism in men 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. Cyproterone acetate (Androcur): A combined AR antagonist and progestogen/antigonadotropin.
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