5α-Reductase Inhibitors and Prostatic Disease

In 1994, 5α-Reductase inhibitors were identified as a promising new class of drugs with potential applications in treating skin conditions like male pattern baldness, acne, and hirsutism, as well as prostatic hyperplasia and prostate cancer. These inhibitors target type I and II 5α-Reductase enzymes, with cDNA for both enzymes having been cloned. Most orally effective inhibitors are 4-azasteroids, and their efficacy can vary based on species-specific differences and the types of 5α-Reductase present in different species and organs. Treatment with these inhibitors can lead to a significant decrease in plasma dihydrotestosterone (DHT) levels by approximately 65%, with a slight increase in plasma testosterone. Tissue DHT levels in the prostate show an even greater reduction of about 85%, accompanied by an increase in tissue testosterone. In men, using a type II 5α-Reductase inhibitor can shrink benign prostatic hyperplasia (BPH) by about 30%, a result also observed in rats, along with a significant reduction in organ DNA, although not as much as with castration.