Finasteride - Proscar - Propecia
Pharmaceutical Name: Finasteride
Drug Classification: Reductase Inhibitor
Active Life: 24-48 hours
The drug finasteride is a competitive Type II 5 alpha-reductase inhibitor
originally developed to help alleviate some of the symptoms and causes of benign
prostatic hyperplasia and then later used to treat male pattern baldness.
Finasteride does so via its mechanism by which it inhibits the Type II alpha-reductase
which is the enzyme that converts testosterone to dihydrotestosterone, more
commonly known by its acronym DHT (1). Therefore finasteride helps in blocking
the formation of DHT in users. This is important since 5-alpha-reductase is
found in high concentrations in such areas of the body as the prostate and
scalp. By inhibiting these interactions in these tissues finasteride can help to
reduce the levels of androgenic activity and prevent some conditions from
occurring or reduce their severity.
In terms of the use of finasteride for steroid users, it would be related to the
easing of several androgenic side effects often associated with the use of some
anabolic and androgenic steroids. Of course due to the originally intended
medical purpose of the drug steroid users suffering from prostate conditions due
to their anabolic steroid use could be well served to use a drug such as
finasteride. This will likely ease some of the discomfort caused by the activity
of the DHT in the prostate tissue and related conditions. Similarly the
androgenic activity of DHT in the scalp leading to hair loss can also prevented
in some males with the use of a reductase inhibitor like finasteride. If the
hair loss experienced by the user is related to an increase in the concentration
and/or level of DHT in the tissue the administration of finasteride can help to
reduce or prevent the severity of this side effect. A third side effect that the
drug may help with is oily skin and/or acne. This androgenic side effect may be
prevented or at the very least reduced in severity with the administration of
finasteride. However, anecdotally the results of this have been mixed to say the
least and relatively few users administer the drug for this purpose.
For many these actions of finasteride will seem very similar to that of another
reductase inhibitor, namely dutasteride. However these drugs do have
differences. The major difference between them is that dutasteride targets both
Type I and Type II 5-alpha reductase. Finasteride only targets Type II (2, 3).
Type I is more heavily concentrated in the liver and skin while Type II is found
most prevalently in male reproductive organs. By targeting both types of the
enzyme, dutasteride is better capable of reducing more DHT then finasteride and
is therefore thought to be more efficient and effective by most. Despite this,
it is still not as popular as finasteride but this is likely due to dutasteride
having been on the market for a much shorter time as well as not currently being
approved medically for use as a preventative measure against male pattern
Finasteride has also been used as a so-called ï¿½masking agentï¿½ by some steroid
users who are tested either via urine or blood (4). While the mechanism by which
this is accomplished will not be discussed in this profile, it should however be
noted that most organizations now recognize this fact and will test for
finasteride along with anabolic steroids. For this reason users of finasteride
who may be tested for such substances should be aware of this fact beforehand.
Use/Dosing of Finasteride
In terms of dosing for the drug, while topical application of finasteride can
yield results, most physicians will recommend and most users will choose to
administer the drug orally. This is due to the greater rate of bioavailability
compared to topical application. The bioavailability of finasteride, when taken
orally, ranges in the area of sixty-five percent of a one milligram tablet in
clinical studies (5). It should also be noted that the bioavailability of
finasteride was not affected when taken with or without food or liquids. Maximum
suppression of DHT conversion occurs within twenty-four hours of administering a
one milligram dose orally. This maximum suppression is approximately sixty-five
of the total DHT conversion (5).
As for the size of dosage required, it depends on the reaction of the user. Most
males that are prescribed finasteride as part of a medical treatment are most
often given doses of one milligram per day. This may be more then necessary
however. Anecdotally some users have indicated that doses of .5 milligrams per
day or one milligram every other day have had the desired effect for some users.
However other users may require larger doses to reap the benefits of the
compound. For the most part these doses range from 1.5 milligrams per day to as
high as five milligrams per day or higher. When increasing oneï¿½s dosage however
a user should make these increases gradually so as to gage their response to the
compound and avoid a dramatic onset of negative side effects.
Finasteride is still a relatively new drug on the market and long-term studies
on it continue to be done. However there are no indications that users have to
limit themselves in regard to the duration of their use of the drug. It was
designed to be administered for long periods of time and is seemingly well
tolerated by the majority of users. For this reason steroid users should feel
free to use finasteride for extended periods of time if they feel it necessary.
The only limiting factors being any side effects that arise for the individual
taking the compound or else the cost of the drug itself, or of course the fact
that it is no longer required. Also, when discontinuing the use of finasteride
there appears no need for a tapering of the drug to prevent a major rebound in
DHT levels of the user. While obviously these levels will return to their normal
concentrations no dramatic rise should be seen by the user.
Risks/Side Effects of Finasteride
For the most part the side effects associated with the use of finasteride are
relatively minor and will not jeopardize the general health of the user. It
appears that all of the reported side effects are related to its action as a
reductase inhibitor and the lack of dihydrotestosterone (DHT) circulating in the
system of the user when using this drug. Toxicity is not a concern as even with
extremely large doses run for long durations (eighty milligrams per day for a
total of three months in one study ) no adverse reactions are observed.
The most common side effect reported with the administration of finasteride is
seemingly sexual dysfunction and/or a reduction in sex drive (6). This is due to
DHT playing a significant role in sex drive with it also being found in high
concentrations in male sex organs playing a role in their proper function. To a
lesser extent some users report that their strength is reduced when using
finasteride and this can also be directly related to the drop in DHT present in
the user. Similarly this may also result in a small reduction in muscle mass
depending on the amount inhibited and the individual body chemistry of the user.
Despite the lack of long term side effects for users there is one significant
side effect that may affect some males. This is namely temporary sterility (7).
This effect does appear to be only temporary with no long term damage to the
ability of the user to produce healthy sperm capable of procreation once
administration of the drug ceases. However users hoping to bear children will
likely have to discontinue their use of the drug to enhance their chances of
success. Finasteride is so successful at causing temporary sterility in males
that it has been studied as part of a combination of drugs that could be used as
male birth control. However these studies remain in their preliminary stages. In
any case, many steroid users will already be experiencing temporary sterility
due to their use of anabolic steroids so this will not be an additional burden
for the vast majority of users.
DHT exhibits the ability to compete for the opportunity to bind to the aromatase
enzyme. If the amount of DHT is reduced this could cause an increase in the
chance that estrogenic side effects (such as water retention, gynocomastia,
etc.), due to less competition for the aromatase enzyme, could arise.
Aromatizable compounds such as testosterone therefore have a greater likelihood
to attach to this enzyme and estrogen levels could increase. While this may not
be a significant problem for most users an increase in estrogenic side effects
may be experienced by some who include finasteride in their cycle(s) so greater
attention may be needed to be paid to such concerns.
It should also be noted that finasteride products should not be handled by
pregnant or lactating women. Birth defects could occur and it is unknown whether
finasteride is excreted in human breast milk; if so this could be harmful to a
nursing child. It is also because finasteride can be absorbed fairly well
through the skin that it should not be touched or handled by women who may be or
are pregnant or nursing (8).
1. Finn DA, Beadles-Bohling AS, Beckley EH, Ford MM, Gililland
KR, Gorin-Meyer RE, Wiren KM. A new look at the 5alpha-reductase inhibitor
finasteride. CNS Drug Rev. 2006 Spring;12(1):53-76.
2. Robaire B, Henderson NA. Actions of 5alpha-reductase inhibitors on the
epididymis. Mol Cell Endocrinol. 2006 May 16;250(1-2):190-5.
3. Makridakis N, Reichardt JK. Pharmacogenetic analysis of human steroid 5 alpha
reductase type II: comparison of finasteride and dutasteride. J Mol Endocrinol.
4. Graf-Baumann T. Medicolegal aspects of doping in football. Br J Sports Med.
2006 Jul;40 Suppl 1:i55-7.
5. RxCC Rx Care Canada. Website:
6. Makridakis N, Reichardt JK. Pharmacogenetic analysis of human steroid 5 alpha
reductase type II: comparison of finasteride and dutasteride. J Mol Endocrinol.
7. Matthiesson KL, Stanton PG, O'Donnell L, Meachem SJ, Amory JK, Berger R,
Bremner WJ, McLachlan RI. Effects of testosterone and levonorgestrel combined
with a 5alpha-reductase inhibitor or gonadotropin-releasing hormone antagonist
on spermatogenesis and intratesticular steroid levels in normal men. J Clin
Endocrinol Metab. 2005 Oct;90(10):5647-55.
8. Iorizzo M, Vincenzi C, Voudouris S, Piraccini BM, Tosti A. Finasteride
treatment of female pattern hair loss. Arch Dermatol. 2006 Mar;142(3):298-302.
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