PNU 157706, a novel dual type I and II5α-reductase inhibitor

PNU 157706 was identified as a potent inhibitor of both type I and II 5α-reductase enzymes, surpassing the efficacy of finasteride, a known inhibitor. It demonstrated IC50 values of 3.9 nM for type I and 1.8 nM for type II 5α-reductase in human recombinant enzymes. In vivo studies showed that PNU 157706 reduced prostatic DHT levels more effectively than finasteride in rats, without binding to the androgen receptor, indicating no anti-androgen activity. The compound also significantly reduced prostate weight in castrated rats implanted with testosterone, but not in those implanted with DHT, suggesting its action is specific to inhibiting 5α-reductase. These results suggest PNU 157706 could be a more efficient therapy for conditions related to DHT, such as benign prostatic hyperplasia and androgenic alopecia.