What is known in the literature concerning Proscar (finasteride) and treatment of androgenic alopec

Fråga: What is known in the literature concerning Proscar (finasteride) and treatment of androgenic alopecia? A young man having experienced androgenic alopecia wants to have this drug prescribed. He has read on Internet of studies showing positive results in this aspect.

Sammanfattning: Preliminary data, however in few patients, has indicated a possible positive effect of finasteride in treating androgenic alopecia. Further documentation is, however, required.

Svar: Finasteride is an orally active 5-alpha-reductase inhibitor mainly used for prostatic hyperplasia. The enzyme 5-alpha-reductase catalyses the conversion of testosterone to dihydrotestosterone (DHT). DHT is the active androgen involved in the development of hair loss

(1).

The enzyme 5-alpha-reductase occurs in two isoforms. The type-1 isoenzyme is expressed in skin tissue throughout the body and the type 2 isoenzyme, which is the dominant form of the enzyme, in genital tissue including the prostate (1).

The loss of scalp hair in male pattern baldness is under androgen control. Male-pattern baldness does not develop in men with 5-alpha-reductase deficiency even though they have normal type-1 5-alpha-reductase activity. Type-2 5-alpha-reductase seems to be important for the development of baldness, despite the data indicating that the type-1 isoenzyme is the dominant form in adult scalp (1).

Finasteride which has a higher affinity for the type-2 isoenzyme has also shown to be an inhibitor of type-1 isoenzyme (2).

Some studies have indicated that finasteride can stimulate hair growth and could be effective in treating male baldness (3,4).

In a double blind study, eight male patients (versus nine placebo) undergoing hair transplantation, were treated with finasteride 5 mg orally per day for 28 days. Scalp skin biopsies were obtained from the balding area initially (baseline) and after 28 days of treatment. The results showed that baseline levels of DHT were significantly higher in bald compared to hair-containing scalp samples. In the finasteride group, five patients with the highest baseline levels of DHT showed a decrease in DHT on day 28, whereas three patients with the lowest DHT levels showed little or no change (3).

Presently, finasteride is approved only for treatment of benign prostatic hyperplasia. However, MSD has an application for registration at the Medical Product Agency concerning finasteride (tablets 1.0 mg) and treatment of androgenic alopecia (5).

Expected untoward effects of finasteride are impotence, around four per cent of patients, decreased libido, around three per cent of patients (6) and reduction in semen volume up to 25 per cent can be expected in some patients (7).

It is not known what other types of adverse effects eg on the prostata that could appear in a young man taking finasteride due to androgenic alopecia.