 Nilutamide is a nitroaromatic hydantoin analog of flutamide, as seen in figure 5.Nilutamide is eliminated exclusively by metabolism, mainly by reduction of the aromatic nitro group.Although the hydrolysis of one of the carbonyl functions of the imidazolinedione was identified, it is much less susceptible to hepatic metabolism than the amide bond in hydroxuflutamide.