Pharmaceutical Name: Dutasteride
Drug Classification: Reductase Inhibitor
Active Life: 24-48 hours
Dutasteride is a reductase inhibitor initially developed and approved for
medical use in the treatment of benign prostatic hyperplasia (1). This is
accomplished via the inhibition of 5-alpha-reductase. 5-alpha-reductase is an
enzyme, which when it interacts with testosterone , produces
dihydrotestosterone (DHT). Therefore dutasteride 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 dutasteride 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 dutasteride 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 dutasteide (2). 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 dutasteride. 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 dutasteride 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 dutasteride. 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 dutasteride will seem very similar to that of
another reductase inhibitor, namely finasteride. 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
(3, 4). 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 baldness.
Interestingly, one study conducted with orally ingested testosterone
accompanied by the ingestion of dutasteride resulted in a higher total serum
testosterone level in those that were being administered both compounds rather
then simply the testosterone itself (5). Of course this result was likely
produced when the conversion of DHT was inhibited by the administration of
dutasteride, but this is simply speculation. This finding is obviously
premature to apply for the purposes of most anabolic steroid users. It does
however offer some insight into the future use of the drug and what could be
investigated, studied and used in the future.
For the maximum suppression of DHT levels that dutasteride can accomplish it
appears that a dose of approximately .5 milligrams per day is required. After
two weeks of this dosing it has been shown that a ninety percent reduction in
DHT levels in the body can be achieved (6). However many users will not
require a dose that large to achieve the results that they are looking for,
namely the prevention of androgenic side effects, etc. Many users will use
smaller doses in the range of .25mgs every day or .5mgs every other day.
However due to the active life of the compound, twenty-four to forty-eight
hours, every other day dosing is as infrequently as one should administer the
drug. As always users should begin using the drug at the smallest dose that
delivers the results that they are looking for to ensure that the severity of
the side effects of the drug are minimized.
When discontinuing the use of dutasteride 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. As well, at this time there appears no
maximum duration that users should limit themselves to when using dutasteride.
As will be described below, there are no long term side effects associated
with the continuous use of this drug other then temporary sterility, however
as will be explained below this condition appears to be only temporary and
should not be a major concern for most users (7).
Dutasteride is administered orally with the absorption rate of the drug not
being affected by the inclusion or exclusion of food or liquids with its
ingestion. Users should feel free to administer the drug with or without any
food they wish while also taking note that there is little suggestion that
stomach discomfort will take place when ingesting the compound.
In terms of side effects related to the use of dutasteride, it appears that
all 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. There are no toxicity issues related to the use of dutasteride and
there have been seemingly no serious related side effects to the long term use
of the drug in males (8, 9).
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. Dutasteride 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.
As for the possible side effects related to the inhibition of DHT the most
frequently reported side effect from use of a reductase inhibitor such as
dutasteride, as reported both in the available research as well as anecdotally
among anabolic steroid users, is a reduction in libido (2). 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
dutasteride 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
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 dutasteride in their
cycle(s) so greater attention may be needed to be paid to such concerns.
1. Kaplan SA. The dual 5-alpha-reductase inhibitor dutasteride
induces atrophic changes and decreases relative cancer volume in human
prostate. J Urol. 2006 Aug;176(2):677.
2. Evans HC, Goa KL. Dutasteride. Drugs Aging. 2003;20(12):905-16.
3. Robaire B, Henderson NA. Actions of 5alpha-reductase inhibitors on the
epididymis. Mol Cell Endocrinol. 2006 May 16;250(1-2):190-5.
4. Makridakis N, Reichardt JK. Pharmacogenetic analysis of human steroid 5
alpha reductase type II: comparison of finasteride and dutasteride. J Mol
Endocrinol. 2005 Jun;34(3):617-23.
5. Amory JK, Bremner WJ. Oral testosterone in oil plus dutasteride in men: a
pharmacokinetic study. J Clin Endocrinol Metab. 2005 May;90(5):2610-7.
6. Llewellyn, William, Anabolics 2004, 2003-4, Molecular Nutrition, p. 260.
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. Roehrborn C, Boyle P, Nickel J, Hoefner K, Andriole G. Efficacy and safety
of a dual inhibitor of 5-alpha-reductase types 1 and 2 (dutasteride) in men
with benign prostatic hyperplasia. Urology 2002 Sep;60(3):434.
9. Schulman C, Pommerville P, Hofner K, Wachs B. Long-term therapy with the
dual 5alpha-reductase inhibitor dutasteride is well tolerated in men with
symptomatic benign prostatic hyperplasia. BJU Int. 2006 Jan;97(1):73-9.
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