The Effect of Zanoterone, a Steroidal Androgen Receptor Antagonist, in Men with Benign Prostatic Hyperplasia

Purpose: Zanoterone (100 to 800 mg.) versus placebo was studied in 463 patients with benign prostatic hyperplasia. Materials and Methods: Study end points were maximum urinary flow rate, American Urological Association symptom index, prostate volume, prostate specific antigen and sex steroid concentrations after 6 months of treatment. Results: Mean increases in maximum urinary flow rate were 2 to 3-fold over placebo, although only the 200 mg. group had significant results (1.7 ml. per second, p = 0.026). There were no statistically significant differences between the zanoterone and placebo groups in symptom index or prostate volume. Estradiol and testosterone concentrations, and the incidence of breast pain and gynecomastia increased significantly with zanoterone compared with placebo. Prostate specific antigen levels decreased significantly. Conclusion: Zanoterone did not demonstrate a favorable risk-to-benefit profile for the treatment of benign prostatic hyperplasia.