Propecia (Finasteride) for Hair Loss
Propecia (Finasteride) is a specific type II 5-alpha reductase inhibitor indicated for the treatment of:
Finasteride inhibits the enzyme responsible for regulating conversion of testosterone to powerful androgenic hormone dihydrotestosterone (DHT). Balding areas of the scalp are associated high levels of DHT, which induce shrinkage of hair follicles. By reducing DHT levels in the scalp, finasteride decreases the effects of DHT on the hair follicles, preventing the process of hair loss.
Propecia works for mild to moderate male pattern hair loss on the vertex (top of head) and anterior mid-scalp area (middle front of head). There is not sufficient evidence that it works for receding hairlines at the temples.
A 1-mg dose reduces serum levels of DHT by 65% after 24 hours (but does not decrease testosterone levels).
According to the 5-year clinical study2 9 of 10 men who take Propecia have visible results - either regrowth of hair (48%) or no further hair loss (42%). Two of 3 men can expect to regrow hair. A majority of men who took Propecia reported that their bald spot got smaller, their hair loss slowed down, and the appearance of their hair improved.
Taking finasteride for over 5 years can decrease the likelihood of developing further visible hair loss by about 93%4.
When to expect results?
Daily use for three months or more may be necessary until a person will notice increased hair growth. It can take 12 months to see the full benefit and to judge how well it’s working for you.
You will need to take Propecia for as long as you want to grow or maintain your hair.
The combination treatment with oral finasteride and topical minoxidil is more effective than finasteride alone 7, 8.
Topical minoxidil and finasteride combination is effective for maintenance of hair density achieved after treatment with oral finasteride and topical minoxidil 9.
Ketoconazole 2% shampoo is used as an adjunct to oral finasteride to promote more complete suppression of dihydrotestosterone 10.
Mode of action
Male pattern hair loss, or androgenetic alopecia, is an androgen-dependent balding. In genetically susceptible men, dihydrotestosterone (DHT), a potent metabolite of the male androgen testosterone, contributes to miniaturization of hair follicles and a shortened hair growth cycle. The conversion of testosterone to DHT is regulated by the enzyme 5-alpha reductase, which is found primarily in scalp follicles.
Finasteride is a competitive and specific inhibitor of Type II 5-alpha-reductase, an intracellular enzyme that converts the androgen testosterone into 5α-dihydrotestosterone. The type II 5-alpha-reductase isozyme is primarily found in prostate, seminal vesicles, epididymides, and hair follicles as well as liver, and is responsible for two-thirds of circulating DHT.
Finasteride decreases DHT concentrations in the serum and the scalp by up to 70 and 60%, respectively. This prevents the miniaturisation of the scalp hair follicles, leading to reversal of the balding process. Finasteride may affect hair growth through reductions in scalp and serum DHT because the scalp is highly vascularized.
Finasteride has no affinity for the androgen receptor and has no androgenic, antiandrogenic, estrogenic, antiestrogenic, or progestational effects.