General
Description & Use
Used to treat benign prostatic hypertrophy (BPH). BPH commonly
occurs in men over 55 years of age and causes the prostate gland
to enlarge. Also used for hair loss.
Finasteride
marketed as Proscar (5mg), Propecia (1mg), Fincar, Finpecia, Finax,
Finast, Finara, Finalo, Prosteride, Gefina, Finasterid IVAX, Finasterid
and Alternova is an antiandrogen which acts by inhibiting type
II 5-alpha reductase, the enzyme that converts testosterone to
dihydrotestosterone (DHT). It is used as a treatment in benign
prostatic hyperplasia (BPH) in low doses, and prostate cancer
in higher doses. A 2008 study indicates that Finasteride reduces
the rate of prostate cancer by 30% (see below). It is also indicated
for use in combination with doxazosin therapy to reduce the risk
for symptomatic progression of BPH. Additionally, it is registered
in many countries for androgenetic alopecia (male-pattern baldness).
Drug
trade names include Propecia
(1mg strength) and Proscar, both products of Merck & Co. (the
former is marketed for hair loss in male pattern baldness, and
the latter for BPH). There is 1 mg of finasteride in Propecia
and 5 mg in Proscar.
Generic
versions Merck's patent on Finasteride (for the treatment of BPH)
expired in June, 2006. Merck was awarded a separate patent for
the use of Finasteride to treat Male Pattern Baldness. This patent
is set to expire in Nov 2013. Several companies outside the USA
currently manufacture generic finasteride and sell it at a significantly
lower cost than Merck:
Cipla
(trade names Fincar and Finpecia)
Dr. Reddy's (trade names Finax and Finast),
Ranbaxy (trade name Finara) Intas (trade name Finalo)
Aleppo Pharmaceutical (trade name Prosteride)
Side effects
Finasteride is not indicated for use by women. Finasteride is
in the FDA pregnancy category X. This means that it is known to
cause birth defects in an unborn baby. Women who are or who may
become pregnant must not handle crushed or broken finasteride
tablets, because the medication could be absorbed through the
skin. Finasteride is known to cause birth defects in a developing
male baby. Exposure to whole tablets should be avoided whenever
possible, however exposure to whole tablets is not expected to
be harmful as long as the tablets are not swallowed. It is not
known whether finasteride passes into breast milk, and thus should
not be taken by breastfeeding women. Finasteride may pass into
the semen of men, but Merck states that a pregnant woman's contact
with the semen of a man taking finasteride is not an issue for
concern. Finasteride has been linked with depression. The drug
also caused reductions in allopregnanolone, a potent, endogenous
positive modulator of the GABA-A receptor, in very large doses
in rodent studies.
Use
as a treatment for hair loss
In a 5-year study of men with mild to moderate hair loss, 48%
of those treated with Propecia (finasteride 1mg) 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 generally 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 Propecia tablets should be kept away from pregnant
women. Propecia has been shown to be ineffective for treating
hair loss in women.[citation needed] 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 testosterone. Many doctors prescribe it for women,
but not without either careful birth control measures or assurance
that the woman cannot become pregnant.
Effects
of Propecia
DHT is a derivative hormone (metabolite) of testosterone that
has been shown to be critical to the initiation and progression
of follicular miniaturization and eventual destruction of hair
follicles in male pattern baldness. DHT is a steroid hormone just
like testosterone but with greater affinity for the androgen receptor.
Converting testosterone to DHT thus increases many of its effects.
While the mechanism by which DHT is involved in hair loss is not
confirmed, many dermatologists and research scientists specializing
in hair loss believe DHT molecules may diffuse into the interior
of hair follicle cells (the cytoplasm or cytosol) and bind with
androgen receptors. This complex, both the receptor and the DHT
molecule, then enters the nucleus of the cell. In the nucleus
of the hair follicle cell this complex could then alter the rate
of protein synthesis in men who are genetically predisposed to
baldness.[citation needed] However, DHT also plays an important
role in the functioning of the central nervous system (the brain),
the testicles and prostate, and almost everything but muscle tissue.
In
muscle tissue testosterone is the dominant hormone, which is why
some bodybuilders inject testosterone derivatives to aid in muscular
development. Propecia (and other products containing finasteride)
causes a rise in testosterone levels, because testosterone that
would normally be converted into DHT remains testosterone. Continual
high levels of testosterone in the body could possibly have negative
side effects. Artificially low levels of DHT in the body could
cause some unwanted conditions. DHT is an antagonist of estrogen.
Men’s bodies also produce the female hormone estrogen in the adrenal
glands, although this is just one-tenth of the estrogen that premenopausal
women produce in their ovaries. By reducing DHT with drugs, a
man’s protection from the effects of estrogen may also be reduced.
This could result in gynecomastia. Even though both finasteride
and dutasteride were developed to combat benign prostatic hyperplasia
by reducing DHT in prostate tissue, some scientists question the
wisdom of using these 5-alpha reductase inhibitors in younger
men who have no problem with their prostates.
