Male pattern baldness (MPB) has plagued men since the beginning of time. While it is considered part of the aging process, a little less than half of the male population does not show patterns of baldness until their late forties to early fifties if at all. It is a response of the body to hormonal changes where some men are more sensitive than others are.
Hormones change with the growth and aging process. Sex hormones increase at puberty, reach a maintenance level during peak fertility, and wane at the later part of life. These hormones affect the appearance of the body to signal to potential mates they male is fertile.
MPB is the body's response to the production of Dihydrotestosterone post puberty. Dihydrotestosterone is responsible for male sexual development. It contributes to the development of the genitals and body hair. It affects production of sperm cells in the testes, growth of the prostate and affects libido.
Propecia (Finasteride) development
The body continues dihydrotestosterone after puberty. Its negative effects are predominantly on the prostate and scalp hair. It is the major cause of prostate enlargement and male pattern baldness. Merck pharmaceuticals developed Finasteride after studies in the late seventies looked at low dihydrotestosterone production in pubertal males and its affects. They found that these boys had smaller prostates, and did not produce the normal sexual body hair. The subjects lack a sufficient quantity of an enzyme that bound to dihydrotestosterone making it active. They created Finasteride, to mimic this affect in males that produce enough of the enzyme. They tested Finasteride to see if it could inhibit the enzyme that allows the body to react to dihydrotestosterone and stop the benign prostatic hyperplasia (BPH: enlargement of the prostate). It did. The FDA approved Finasteride as a type 2 a reductase (the enzyme needed to work with dihydrotestosterone) inhibitor for the treatment of BPH (benign prostatic hyperplasia).
A reported side effect of Finasteride for BPH was participant's fond their hair was growing back, and showed a reversal or MPB. After a 5-year study on its affects on hair loss, the FDA gave approval to list hair re-growth as a use for Finasteride and Merck began marketing it under the name of Propecia in 1997. Since then Propecia pills has been one of the few FDA approved proven treatments to effectively reduce and in some cases reverse male pattern baldness.