Finasteride (marketed as Proscar, Propecia, Fincar, Finpecia, Finax, Finast, Finara, Finalo, Prosteride, Gefina, Appecia, Finasterid IVAX, Finasterid Alternova, Hyplafin, Penester, Finpros, Tectum, Prezepa) is a synthetic antiandrogen that acts by inhibiting type II 5-alpha reductase, the enzyme that converts testosterone to dihydrotestosterone (DHT). Finasteride was initially approved by the U.S. Food and Drug Administration (FDA) in 1992 under the brand name Proscar, a treatment for benign prostatic hyperplasia (BPH). In 1997, the FDA approved finasteride to treat male pattern baldness (MPB), under the brand name Propecia.
Finasteride is used in the treatment of prostate cancer,
benign prostatic hyperplasia, and androgenetic alopecia (male pattern
baldness).
Benign prostatic hyperplasia
Finasteride is used for the treatment of benign prostatic
hyperplasia (BPH) (also known as enlarged prostate) at a dose of 5 mg
once a day. It may take six months or more to see the full effects of
finasteride. If the drug is discontinued, any therapeutic benefits will
be reversed. Finasteride may improve the symptoms associated with BPH
such as difficulty urinating, getting up during the night to urinate,
hesitation at the start of urination, and decreased urinary flow.
Hair loss
In a 5-year study of men with mild to moderate hair loss,
48% of those treated with Propecia (finasteride 1 mg) experienced some
regrowth of hair, and a further 42% had no further loss. Average hair
count in the treatment group remained above baseline, and showed an
increasing difference from hair count in the placebo group, for all five
years of the study. Propecia is effective only for as long as it is
taken; the hair gained or maintained is lost within 6–12 months of
ceasing therapy. In clinical studies, Propecia, like minoxidil, was
shown to work on both the crown area and the hairline, but is most
successful in the crown area.
Some users, in an effort to save money, buy Proscar instead
of Propecia, and split the Proscar pills to approximate the Propecia
dosage. Doing so is considered unadvisable if women of pregnancy age are
in the household; this is because finasteride, even in small
concentrations, can cause birth defects in a developing male fetus. The
birth defects involve the development of male genitalia (no such effects
have been noted in developing female fetuses). On most product inserts,
it will be mentioned that the dust or crumbs from broken Proscar
tablets should be kept away from pregnant women.
Propecia has been shown to be ineffective for treating hair
loss in women. However, Propecia's supporters respond that the study was
on post-menopausal women whose hair loss was more likely related to the
loss of estrogen versus a sensitivity to DHT. Doctors may prescribe it
for women, but not without sufficient birth control measures in place or
assurance that the woman cannot become pregnant.
Prostate cancer
The use of finasteride to prevent prostate cancer is
controversial. Some urologists believe it can prevent prostate cancer,
while others believe that it merely shrinks low-grade tumors that would
not be lethal, and may even delay detection of cancers until they become
high-grade and are difficult to treat.
The 2005 Prostate Cancer Prevention Trial (PCPT) showed at a
dosage of 5 mg per day, as is commonly prescribed for BPH, participants
taking finasteride were 25% less likely to have developed prostate
cancer at the end of the trial compared to those taking a placebo. It
appeared (incorrectly) that finasteride increased the specificity and
selectivity of prostate cancer detection, thus creating an apparently
increased rate of high Gleason grade tumor. A 2008 update of this study
found that finasteride reduces the incidence of prostate cancer by 30%.
In the original study, it turns out that the smaller prostate caused by
finasteride means that a doctor is more likely to hit upon cancer nests
and more likely to find aggressive-looking cells. Most of the men in the
study who had cancer — aggressive or not — chose to be treated, and
many had their prostates removed. A pathologist then carefully examined
each of those 500 prostates and compared the kinds of cancers found at
surgery to those initially diagnosed at biopsy. This study concluded
that Finasteride did not increase the risk of high-grade prostate
cancer.
Further Reading
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