Mechanism of finasteride

Finasteride inhibits an enzyme which converts testosterone to another androgen called dihydrotestosterone (DHT). DHT plays a crucial role in male sexual development.

The enzyme finasteride inhibits is called 5-alpha reductase (5-AR). People born with a deficiency of this enzyme may appear to be girls at birth but develop male characteristics at puberty. Because they have small prostates and their hairline does not recede in adulthood, Merck sought to develop a drug that would induce a deficiency of the 5-AR enzyme in adult men. Learn more about the origins of finasteride

For details on the drug mechanism, see: