Male pattern baldness

Male pattern baldness (androgenetic alopecia) is one of the major types of hair loss in men.
It is characterized by loss of hair from the top or above the temple areas or both.
In these areas, the anagen (hair growing phase) shortens and the hair at the surface of these areas shrinks and finally disappears.
Male pattern baldness tends to run in the family. The 5 α-reductase, an enzyme responsible for converting testosterone (a major sex hormone in males) into dihydrotestosterone (DHT), a main pathologic metabolite in male pattern baldness has two subtypes; 5 α-reductase type 1 and 5 α-reductase type 2.
Among these two subtypes, 5 α-reductase type 2 is more actively involved in the conversion of testosterone into DHT in the root of hair of the aforementioned area of the scalp and the prostate where it is expressed.
On the other hand, 5 a-reductase type 1 is expressed not only on the top of the scalp but also in the hair follicles of the back of the scalp and armpits.

Finasteride 1mg improved male pattern baldness in approximately 80% of the subject in 3-year administration.
Dutasteride 0.5 mg reportedly significantly increased hair count and width and improved hair growth at week 24 compared with finasteride 1 mg. Both medications are known to reduce semen volume by more than 20 %, more decrease of average semen was reported with those taking dutasteride.
Also these medication reportedly produce sexual dysfunction to a certain extent.
Hepatotoxicity can be induced and a regular checkup of a liver function is necessary.