Finasteride

Finasteride is a synthetic polycyclic steroid used to treat male benign prostatic hyperplasia, hair loss, and as hormone therapy for transsexual women. It works by inhibiting the enzyme 5α-reductase, which converts testosterone to dihydrotestosterone (DHT). By reducing DHT levels in the blood and scalp, finasteride slows the progression of androgenic alopecia. The drug specifically targets type II 5α-reductase, which is expressed in the prostate and hair follicles.