Androgen antagonists37 bind to the receptor and prevent binding of the natural steroids, but they do not produce the correct conformational change in the receptor that is essential to elicit normal changes in gene expression. Cyproterone is a steroidal antiandrogen that was initially developed as a synthetic gestagen to be used as a contraceptive, but the observation of feminization of the offspring in gestating rats led to its identification as a competitive inhibitor of the AR. It is used in prostatic carcinoma, but its side effects of gynecomastia and edema, which can be attributed to its analogy with natural gestagens and glucocorticoids, respectively, stimulated the search for nonsteroidal compounds with pure antiandrogenic action (SARM, selective androgen receptor modulators).
H3COC H3CO ~
Flutamide was the first nonsteroidal antiandrogen. In itself it does not act on ARs, but it is metabolized by hydroxylation to the active species. This metabolite inhibits both androgen uptake and binding of androgens to their receptors in target tissues. Other antiandrogens that are in clinical use for the treatment of prostate cancer are bicalutamide and nilutamide, which have the advantage over flutamide of having a higher half-life that allows its administration only once daily.
H3COC H3CO ~
Was this article helpful?