Flutamide (brand name Eulexin) is a synthetic, non-steroidal antiandrogen (NSAA) used primarily to treat prostate cancer. It acts as a selective antagonist of the androgen receptor (AR), competing with androgens such as testosterone and its powerful active metabolite dihydrotestosterone (DHT) for binding to ARs in the prostate gland. By doing so, it prevents them from stimulating the prostate cancer cells to grow. In addition to its use in prostate cancer, flutamide has been used to treat hyperandrogenism (excess androgen levels) in women, such as in those with polycystic ovary syndrome (PCOS), and hirsutism. Flutamide has been largely replaced by newer NSAAs, namely bicalutamide and enzalutamide, due particularly to better safety, tolerability, and pharmacokinetic profiles.