Flutamide is a nonsteroidal antiandrogen. In animal studies, flutamide demonstrates potent antiandrogenic effects. It exerts its antiandrogenic action by inhibiting androgen uptake and/or by inhibiting nuclear binding of androgen in target tissues or both. Prostatic carcinoma is known to be androgen-sensitive and responds to treatment that counteracts the effect of androgen and/or removes the source of androgen, e.g. castration. Elevations of plasma testosterone and estradiol levels have been noted following flutamide administration. Flutamide blocks the action of both endogenous and exogenous testosterone by binding to the androgen receptor. In addition Flutamide is a potent inhibitor of testosterone-stimulated prostatic DNA synthesis. Moreover, it is capable of inhibiting prostatic nuclear uptake of androgen. Flutamide is used for the management of locally confined Stage B2-C and Stage D2 metastatic carcinoma of the prostate.

Hydroxyflutamide is the major active metabolite of flutamide. Flutamide undergoes extensive first-pass metabolism by CYP1A2 to its metabolite hydroxyflutamide and its hydrolysis product, 3-trifluoromethyl-4-nitroaniline. Hydroxyflutamide is a more powerful antiandrogen in vivo, with higher affinity for the receptor than that of flutamide. Hydroxyflutamide is in phase II clinical trials for the treatment of prostate cancer. However, a drug resistance problem appears after about one year's treatment. Per-residue free energy decomposition analyses indicate that N705, T877, and M895 androgen receptor mutations are vital residues in the agonist/antagonist mechanism of hydroxyflutamide.

4-Nitro-3-trifluoromethylaniline is one of the two main products of flutamide metabolism in human liver microsomes. Also, it is a major urinary metabolite of S-1 [3-(4-fluorophenoxy)-2-hydroxy-2-methyl-N-[4-nitro-3-(trifluoromethyl)phenyl]-propanamide] - a member of a series of potent selective androgen receptor modulators.

3-Trifluoromethylisobutyranilide is one of Flutamide impurity.