Flutamide

Abstract

Flutamide is an oral nonsteroidal antiandrogen drug primarily used to treat prostate cancer. The in vivo metabolism of flutamide was studied in patients with prostate cancer receiving oral dosing (125 mg, thrice daily). Circulating metabolites detected were a side‐chain monohydroxylation metabolite and the amide hydrolysis metabolite and its N ‐acetyl conjugate. Major metabolites found in urine were side‐chain mono‐ and trihydroxylation metabolites, and the further aryl hydroxylation product of the amide hydrolysis metabolite. Nitro‐reduction to the corresponding amine was also an important metabolic reaction. In a separate human metabolism study, after an oral dose of 250‐mg flutamide, sulfate, GSH, and glucuronide conjugates of flutamide and its hydroxylated metabolites were also identified in urine.