The novel drug CS-891 inhibits 5alpha-reductase activity in freshly isolated dermal papilla of human hair follicles.

The study investigated the ability of the novel drug CS-891 to inhibit 5alpha-reductase (5aR) activity in the dermal papillae of human hair follicles, which is crucial for the treatment of androgenetic alopecia (AGA). While finasteride, a selective type II 5aR inhibitor, was known to reduce circulating dihydrotestosterone (DHT) by 60-70% in men, it did not affect type I 5aR activity, leaving some DHT production unaffected. CS-891, with its dual inhibitory action on both type I and type II 5aR, was proposed as a potentially effective treatment for AGA by targeting the hair follicles directly. The study demonstrated that CS-891 could inhibit 5aR activity in its target tissue, suggesting its potential effectiveness in preventing or treating AGA.