Finasteride is not new. The drug, which works by blocking the conversion of testosterone to dihydrotestosterone or DHT (chart), has been used since 1992 to treat prostate enlargement. But lower doses have been shown to slow thinning and promote growth in some men with mild to moderate hair loss. In clinical trials of 1,553 users, 86 percent maintained or increased their hair count. Forty-two percent of men who received a placebo also showed improvement, probably due to the placebo effect and cyclical hair growth. The once-a-day pill, which takes months to work, appears more effective on the top of the head than on the front.
The FDA panel expressed some safety concerns about the drug, whose brand name is Propecia. Side effects in about 4 percent of men studied included decreased libido and difficulty achieving an erection. And the drug can cause birth defects, so it will not be prescribed to women. ““This is not going to be the big cure-all,’’ says Dr. Peter Proctor, a drug researcher in Houston. Maybe not. But with few other effective remedies, plenty of balding men will want to get their hands on that pill.
DHT production The enzyme 5AR converts the male hormone testosterone into a more active form called DHT
Balding DHT binds to the base of hair follicles and, in men susceptible to balding, causes the follicles to shrink.
Restored By blocking the action of 5AR, Propecia reduces exposure to DHT and helps restore follicles.
