Flutamide (SCH 13521) is an antiandrogen with about the same potency as cyproterone in rodent and canine species.

Androgen receptor:55 nM(Ki)

Flutamide significantly reduced the prostate weight in rats from 319 mg to 245 mg. Co-administration of Flutamide with a luteinizing hormone-releasing hormone (LHRH) agonist compounded side effects, further decreasing prostate weight to 101 mg and markedly diminishing prostatic ornithine decarboxylase (ODC) activity.

The concurrent use of Flutamide and leuprorelin can be employed in the treatment of prostate cancer. The active metabolite of Flutamide, Flutamide-OH, binds directly to the androgen receptors in the anterior pituitary of rats (Ki=55 nM). Flutamide does not affect the proliferation of androgen-sensitive clones in the Shionogi SC-115 mouse mammary carcinoma cells when cultured, displaying only antiandrogenic effects without any androgenic activity.

Androgen Receptor Assay: Aliquots of 100 μl cytosol are incubated at 0-4°C for 18 h with 100 μl of the indicated saturating concentration of [3H]T in the presence or absence of increasing concentrations of nonlabeled T, DHT, flutamide (FLU) or flutamide-OH (FLU-OH). At the end of the incubation, free and bound T are separated by the addition of 200 μl dextran-coated charcoal (1 % charcoal, 0.1% dextran T-70, 0.1% gelatin, 1.5 mM EDTA and 50 mM Tris (pH 7.4)) for 15 min before centrifugation at 2300 × g for another 15 min at 0-4°C. Aliquots (350 μl) of the supernatant are transferred to scintillation vials with 10 ml of an aqueous counting solution before counting in a Beckman LS 330 counter.

Effect of flutamide on the growth of an androgen-sensitive clone (SEM-l) of mouse mammary carcinoma Shionogi cells in culture. The cells are incubated up to 40 days in medium (MEM + 2% dextran-coated charcoal extracted fetal calf serum) containing the compounds at a concentration of 1 μM. Media are changed every second day.(Only for Reference)