Finasterid是5-α还原酶抑制剂,它竞争性地阻断5-a还原酶,这种酶使睾酮还原为原来的活性型二氢睾酮。给予单剂量本品后,二氢睾酮浓度迅速下降,而血浆中睾酮浓度不变。本品的疗效,在两次为期一年、以安慰剂为对照的双盲前瞻性研究中得到证实。这两次研究仍在进行,已临床1645例。在头一年临床中,有中度至严重症状的病人服用本品后,症状明显改善,前列腺缩小20～50％,排尿速度加快。对543例病人观察24个月, Finasterid, a 5-alpha reductase inhibitor, competitively blocks 5-a reductase, an enzyme that reduces testosterone to its original active dihydrotestosterone. Given a single dose of this product, the dihydrotestosterone concentration decreased rapidly, while the plasma testosterone concentration unchanged. The efficacy of this product, in a two-year period, placebo-controlled double-blind prospective study was confirmed. These two studies are still ongoing, has been clinically 1645 cases. In the first year of clinical, patients with moderate to severe symptoms after taking this product significantly improved the symptoms, prostate reduced 20 ~ 50%, urination speed. 543 patients observed for 24 months,