A toluidine derivative and nonsteroidal antiandrogen that is structurally related to bicalutamide and nilutamide. Flutamide and its more potent active metabolite 2-hydroxyflutamide competitively block dihydrotestosterone binding at androgen receptors, forming inactive complexes which cannot translocate into the cell nucleus. Formation of inactive receptors inhibits androgen-dependent DNA and protein synthesis, resulting in tumor cell growth arrest or transient tumor regression. or A drug used with another drug to treat certain types of prostate cancer. Flutamide binds to proteins called androgen receptors, which are found in some prostate cancer cells, and keeps androgens (male hormones) from binding to the receptors. This blocks the ability of androgens to cause prostate cancer cells to grow. Flutamide is a type of antiandrogen.