Proscar® (finasteride) dht blocker profile and use in sports

akn · Jul 5, 2014

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Finasteride is an inhibitor of 5a-reductase, which is the

enzyme responsible for converting testosterone into DHT
(dihydrotestosterone). This drug can efficiently reduce the
serum concentration of DHT, thereby minimizing the
unwanted androgenic effects that result from its presence.
The effect of this drug is quite rapid, suppressing serum DHT
concentrations as much as 65% within 24 hours after taking a
single 1mg tablet. Medically, this drug is used to treat benign
prostate hyperplasia (prostate enlargement) and androgenetic
alopecia (male pattern hair loss). It is also being investigated
as a potential treatment for hirsutism, which describes male
patterned hair growth on the face or body of a woman. Male
athletes and bodybuilders are interested in finasteride for its
ability to reduce the androgenic side effects associated with
the use of testosterone and certain derivatives.
Finasteride is a specific inhibitor of the Type-II 5a reductase
enzyme. There are actually two isozymes of reductase in the
human body, labeled as Type-I and Type-II. Type-I 5areductase
is predominantly found in the liver and sebaceous
glands of the skin. Type-II 5a-reductase is primarily found in

the prostate and hair follicles. The Type-II enzyme is
responsible for about 2/3rd of the circulating DHT, while the
Type-I enzyme produces the remaining 1/3rd. As an inhibitor
of Type-II reductase only, finasteride has a more pronounced
effect with regard to preventing hair loss, but is somewhat
less effective at mitigating oily skin and acne. Since hair loss
is the primary worry among most male steroid users who use
reductase inhibitors, finasteride remains a popular ancillary
drug in spite of its inability to block DHT conversion in all
tissues.
Finasteride is considered a highly specific drug, as it has
little spillover effect on the other hormones in the body. It
has no affinity for the androgen or estrogen receptors, and
therefore does not exhibit any androgenic, antiandrogenic,
estrogenic, or anti-estrogenic properties. It has no
appreciable impact on circulating levels of cortisol, thyroidstimulating
hormone, or thyroxine, nor does it appear to alter
HDL/LDL cholesterol levels. Changes in luteinizing hormone
(LH) or follicle-stimulating hormone (FSH) are also not
notable, and it is not shown to have a significant effect on the
hypothalamic-pituitary-testicular axis. Finasteride has been
shown to increase the circulating levels of testosterone by
roughly 15%, however, since a greater amount of the
androgen is being left unaltered by the reductase enzyme.
History:

The first release of finasteride in the U.S. was under the
brand name of Proscar® (Merck), which was approved by
the FDA in 1992. It was specifically given approval for use
by patients with benign prostate hyperplasia (prostate
enlargement). In December 1997, the Food and Drug
Administration again approved finasteride, this time for a
different purpose, namely the treatment of male pattern hair
loss. Merck released the drug under a different brand name
for this purpose, Propecia®, which contained only 1/5th of
the Proscar® dosage. Today, both Proscar® and Propecia®
remain the dominant brands of finasteride on the global
market.
How Supplied:
Finasteride is most commonly supplied in tablets of 1 mg and
5 mg.
Structural Characteristics:
Finasteride is a synthetic 4-azasteroid. It has the chemical
designation 4-azaandrost-1-ene-17-carboxamide,N-(1,1-
dimethylethyl)-3-oxo-,(5·,17‚)-.
Warnings (Pregnancy):

This drug must never be taken during pregnancy. Finasteride
can be absorbed through the skin.Women who are, or might
become pregnant, should never handle broken or uncoated
finasteride tablets. The DHT blocking action of finasteride
can cause severe developmental problems to an unborn male
fetus, even in very small amounts. Unaltered finasteride can
also be recovered in the semen.It is unknown if enough drug
can be absorbed during sexual intercourse to harm a
developing male fetus. The use of condoms or abstinence is
recommended during therapy.
Side Effects:
Adverse reactions commonly associated with the short- term
(1 year) use of finasteride include impotence (8.1%),
decreased libido (6.4%), decreased ejaculate volume
located. (3.7%), ejaculation disorder (.8%), gynecomastia
(.5%), breast tenderness (.4%), and rash (.5%).
Administration (General Considerations):
Reductase inhibitors cannot completely protect against
androgenic side effects such as steroid-induced hair loss,
oily skin, and acne. Reductase inhibitors lessen these side
effects by reducing, not eliminating, the level of androgenic
activity in the skin and scalp. Androgenic and anabolic
effects are both mediated by the same receptor, and there is

no way presently known to completely separate these two
properties. Dihydrotestosterone is also not unique in its
ability to facilitate androgenetic alopecia (male pattern hair
loss). DHT inhibition, therefore, does not offer complete
protection against this side effect.
Reductase inhibitors are only applicable with testosterone,
methyltestosterone, and fluoxymesterone. These three drugs
are converted to stronger “dihydro” derivatives by the
reductase enzyme. Nandrolone and some of its derivatives
become weaker upon interaction with this enzyme, as their
“dihydro” metabolites bind the androgen receptor very
poorly. Reductase inhibition may intensify their androgenic
side effects. Methandrostenolone and boldenone undergo
conversion to stronger 5-alpha reduced metabolites, but at
such small levels that reductase inhibitors have little effect
on their androgenicity. Most other synthetic anabolic steroids
are unaffected by the reductase enzyme and reductase
inhibitors.
Administration:
When used medically for the treatment of male pattern hair
loss (androgenetic alopecia) in men, the recommended
dosage is 1mg per day. When used for the treatment of benign
prostatic hyperplasia (BPH), 5 mg per day is usually
administered. When used by bodybuilders and athletes to

reduce the androgenicity of testosterone, methyltestosterone,
or fluoxymesterone, finasteride is commonly taken in a
dosage of 1mg per day. The drug is typically administered
for as long as the offending steroids are also taken. Since
DHT inhibition can lessen strength and possibly muscle gains
during testosterone, methyltestosterone, or fluoxymesterone
therapy (given the positive actions of androgens on the
neuromuscular system), a “use only when necessary”
approach is usually taken with regard to this drug.
Availability:
Finasteride is widely available in most regions of the
world.The most prominent brand names in commerce are
Proscar® (5 mg) and Propecia® (1mg), although a number of
other brand and generic forms of the drug can also be
located.

By WL

Proscar® (finasteride) dht blocker profile and use in sports

akn

Musclechemistry Member

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