Finasteride is more popularly known as Propecia. Propecia is the brand name for finasteride at the 1 mg dose. It is one of the few medications that work for many people. It is usully in table form taken orally.

Male pattern baldness (androgenetic alopecia) is caused by the effects of male hormone dihydrotestesterone (DHT) on hair follicles that are genetically vulnerable. They are usually located in the front, top and crown of the scalp, leaving the back and sides to remain relatively lush.

DHT affects hair loss by shortening the growth phase of the cycle, leading to a minitiarization of the hair follicles. The affected hair grows more slowly or stops growing completely, becoming shorter and finer until it dinally disappears.

The male sex hormones involved in the hair thinning process are testosteerone and DHT. The cells in the body metabolize testosterone and turn it into DHT. This process is facilitated by an anzyme called 5-alpha reductase (5AR). There are two types of 5AR:

Type 1, which is mainly located in the sebaceous (sweat) glands, keratinocytes and fibroblasts. This enzyme catgalizes the conversion if testerone into another hormone called androstenedione which is related to the production of sebum. Its role in hair loss is not clear.Type 2, which is found in the skin and the sheath of hair follicles has a clearer role on hair loss. It appears to cause hair loss for those who are genetically predisposed for hair loss. Finesteride prevents hair loss by blocking the effect of this hormone.

This drug works by making 5AR less potent, reducing its ability to produce DHT. Taken at 1 milligram a day, clinically studies show that ti can reduce the DHT levels by almost 70 percent.

Contrary to popular belief, finasteride does not lower the testerone level. Instead it increase it by 9 percent.