How does finasteride (Propecia) work?
In the hair follicle cells, the enzyme 5-alpha reductase converts testosterone into the more biologically active dihydrotestosterone (DHT). The DHT hormone then binds to receptors in the hair follicle, triggering cellular processes in genetically predisposed hair follicles that reduce the anagen (growing) phase of the hair cycle. It is believed that the prescription drug finasteride, which is a prescription medicine and the active ingredient in Propecia/Proscar, is an inhibitor of 5-alpha reductase, blocking the chemical conversion from testosterone to DHT. This allows those hairs predisposed to inactivity to become active again and make new hairs.
