Durabolin® (nandrolone phenylpropionate)
Description:
Nandrolone phenylpropionate is an injectable form of the anabolic steroid
nandrolone. The properties of this drug are strikingly similar to those of
Deca-Durabolin®, which uses the slower acting drug nandrolone decanoate.
The primary difference between these two preparations is the speed in
which nandrolone is released into the blood. While nandrolone decanoate
provides a release of nandrolone from the area of injection lasting
approximately 3 weeks, nandrolone phenylpropionate is active for only
about a week. In clinical situations, Deca-Durabolin can thus be injected
once every 2 or 3 weeks, while Durabolin® is usually administered every
several days to once weekly. Otherwise, the two drugs are virtually
interchangeable. Like Deca-Durabolin, Durabolin is valued by athletes and
bodybuilders for its abilities to promote strength and lean muscle mass
gains without significant estrogenic or androgenic side effects.
History:
Nandrolone phenylpropionate was first described in 1957.471 It became 
prescription
medication
shortly
after,
sold
by
the
international
pharmaceuticals giant Organon (now Merck/MSD) under the brand name
Durabolin. When first introduced to the United States, indicated uses of
nandrolone phenylpropionate included pre- and postoperative lean mass
retention, osteoporosis, advanced breast cancer, weight loss due to
convalescence or disease, geriatric states (general weakness and frailty),
burns, severe trauma, ulcers, adjunct therapy with certain forms of anemia,
and selective cases of growth and development retardation in children.
During the 1970’s, the FDA began revising the indicated uses of this drug,
however, and they were soon significantly narrowed. Moving forward, the
drug was mainly being indicated for the treatment of advanced metastatic
breast cancer, and as adjunct therapy for the treatment of senile and post-
menopausal osteoporosis.
Durabolin was a key focus of Organon’s marketing efforts only for well less
than a decade following its release. Once Deca-Durabolin was introduced
during the 1960’s, this shorter-acting counterpart, although still available,
started to take a back seat. Durabolin was not completely abandoned by
Organon at the time, however, partly due to the fact that it was given a
slightly different set of therapeutic uses in certain countries, and therefore
continued to hold onto a niche market for some time. As the size of the
anabolic steroid market continued to grow throughout the 1970’s and ’80’s,
it was nandrolone decanoate that was attracting the most attention of other
drug manufacturers. Numerous drug companies had produced their own
versions of nandrolone phenylpropionate over the years, however. Today,
the drug remains scarcely available. It is unknown if the present owner of
Organon (Merck/MSD) will market Durabolin, or if its production (as a
brand name product) has ended.
How Supplied:
Nandrolone phenylpropionate is available in select human drug markets.
Composition and dosage may vary by country and manufacturer, but
usually contain 25 mg/mL or 50 mg/mL of steroid dissolved in oil.
Structural Characteristics:
Nandrolone phenylpropionate is a modified form of nandrolone, where a
carboxylic acid ester (propionic phenyl ester) has been attached to the 17-
beta hydroxyl group. Esterified steroids are less polar than free steroids, and
are absorbed more slowly from the area of injection. Once in the
bloodstream, the ester is removed to yield free (active) nandrolone.
Esterified steroids are designed to prolong the window of therapeutic effect
following administration, allowing for a less frequent injection schedule
compared to injections of free (unesterified) steroid. Nandrolone
phenylpropionate provides a sharp spike in nandrolone release 24-48 hours
following deep intramuscular injection, and declines to near baseline levels
within a week.
Side Effects (Estrogenic):
Nandrolone has a low tendency for estrogen conversion, estimated to be
only about 20% of that seen with testosterone.472 This is because while the
liver can convert nandrolone to estradiol, in other more active sites of
steroid aromatization such as adipose tissue nandrolone is far less open to
this process.473 Consequently, estrogen- related side effects are a much
lower concern with this drug than with testosterone. Elevated estrogen
levels may still be noticed with higher dosing, however, and may cause side
effects such as increased water retention, body fat gain, and gynecomastia.
An anti-estrogen such as clomiphene citrate or tamoxifen citrate may be
necessary to prevent estrogenic side effects if they occur. One may
alternately use an aromatase inhibitor like Arimidex® (anastrozole), which
more efficiently controls estrogen by preventing its synthesis. Aromatase
inhibitors can be quite expensive in comparison to anti-estrogens, however,
and may also have negative effects on blood lipids.
It is of note that nandrolone has some activity as a progestin in the body.474
Although progesterone is a c-19 steroid, removal of this group as in 19-
norprogesterone creates a hormone with greater binding affinity for its
corresponding receptor. Sharing this trait, many 19-nor anabolic steroids are
shown to have some affinity for the progesterone receptor as well.475 The
side effects associated with progesterone are similar to those of estrogen,
including negative feedback inhibition of testosterone production and
enhanced rate of fat storage. Progestins also augment the stimulatory effect
of estrogens on mammary tissue growth. There appears to be a strong
synergy between these two hormones here, such that gynecomastia might
even occur with the help of progestins, without excessive estrogen levels.
The use of an anti-estrogen, which inhibits the estrogenic component of this
disorder, is often sufficient to mitigate gynecomastia caused by nandrolone.
Side Effects (Androgenic):
Although classified as an anabolic steroid, androgenic side effects are still
possible with this substance, especially with higher doses. This may include
bouts of oily skin, acne, and body/facial hair growth. Anabolic/androgenic
steroids may also aggravate male pattern hair loss. Women are warned of
the potential virilizing effects of anabolic/androgenic steroids. These may
include a deepening of the voice, menstrual irregularities, changes in skin
texture, facial hair growth, and clitoral enlargement. Nandrolone is a steroid
with relatively low androgenic activity relative to its tissue-building actions,
making the threshold for strong androgenic side effects comparably higher
than
with
more
androgenic
agents
such
as
testosterone,
methandrostenolone, or fluoxymesterone. It is also important to point out
that due to its mild androgenic nature and ability to suppress endogenous
testosterone, nandrolone is prone to interfering with libido in males when
used without another androgen.
Note that in androgen-responsive target tissues such as the skin, scalp, and
prostate, the relative androgenicity of nandrolone is reduced by its reduction
to dihydronandrolone (DHN).476 477
The 5-alpha reductase enzyme is responsible for this metabolism of
nandrolone. The concurrent use of a 5-alpha reductase inhibitor such as
finasteride or dutasteride will interfere with site-specific reduction of
nandrolone action, considerably increasing the tendency of nandrolone to
produce androgenic side effects. Reductase inhibitors should be avoided
with nandrolone if low androgenicity is desired.
Side Effects (Hepatotoxicity):
Nandrolone is not c-17 alpha alkylated, and not known to have hepatotoxic
effects. Liver toxicity is unlikely.
Side Effects (Cardiovascular):
Anabolic/androgenic steroids can have deleterious effects on serum
cholesterol. This includes a tendency to reduce HDL (good) cholesterol
values and increase LDL (bad) cholesterol values, which may shift the HDL
to LDL balance in a direction that favors greater risk of arteriosclerosis. The
relative impact of an anabolic/androgenic steroid on serum lipids is
dependant on the dose, route of administration (oral vs. injectable), type of
steroid (aromatizable or non-aromatizable), and level of resistance to
hepatic metabolism. Studies administering 600 mg of nandrolone decanoate
per week for 10 weeks demonstrated a 26% reduction in HDL cholesterol
levels.478 This suppression is slightly greater than that reported with an
equal dose of testosterone enanthate, and is in agreement with earlier
studies showing a slightly stronger negative impact on HDL/LDL ratio with
nandrolone
decanoate
as
compared
to
testosterone
cypionate.479
Nandrolone should still have a significantly weaker impact on serum lipids
than c-17 alpha alkylated agents. Anabolic/androgenic steroids may also
adversely effect blood pressure and triglycerides, reduce endothelial
relaxation, and support left ventricular hypertrophy, all potentially
increasing the risk of cardiovascular disease and myocardial infarction.
To help reduce cardiovascular strain it is advised to maintain an active
cardiovascular exercise program and minimize the intake of saturated fats,
cholesterol, and simple carbohydrates at all times during active AAS
administration. Supplementing with fish oils (4 grams per day) and a
natural cholesterol/antioxidant formula such as Lipid Stabil or a product
with comparable ingredients is also recommended.
Side Effects (Testosterone Suppression):
All anabolic/androgenic steroids when taken in doses sufficient to promote
muscle gain are expected to suppress endogenous testosterone production.
Studies administering 100 mg injection of nandrolone phenylpropionate
demonstrated a rapid suppression of serum testosterone following a single
injection. Testosterone levels declined to approximately 30% of initial level
by day 3 after drug administration, and stayed suppressed for approximately
13 days. Regular use is expected to significantly lengthen the endogenous
hormone recovery window. It is believed that the progestational activity of
nandrolone notably contributes to the suppression of testosterone synthesis
during therapy, which can be marked in spite of a low tendency for estrogen
conversion.480 Without the intervention of testosterone-stimulating
substances, testosterone levels should return to normal within 2-6 months of
drug secession. Note that prolonged hypogonadotrophic hypogonadism can
develop secondary to steroid abuse, necessitating medical intervention.
The above side effects are not inclusive. For more detailed discussion of
potential side effects, see the Steroid Side Effects section of this book.
Administration (Men):
For general anabolic effects, early prescribing guidelines recommend a
dosage of 25-50 mg per week for 12 weeks. The usual dosage for physique-
or performance-enhancing purposes is in the range of 200-400 mg per
week, taken in cycles 8 to 12 weeks in length. This level is sufficient for
most users to notice measurable gains in lean muscle mass and strength.
Note that due to the fastacting nature of the phenylpropionate ester, the
weekly dosage is usually subdivided into 2 separate applications spaced
evenly apart.
Administration (Women):
For general anabolic effects, early prescribing guidelines recommend a
dosage of 25-50 mg per week for 12 weeks. When used for physique- or
performance-enhancing purposes, a dosage of 50 mg per week (given in a
single weekly injection) is most common, taken for cycle lasting 4 to 6
weeks. Higher doses or longer durations of use are discouraged due to
potential for androgenic side effects. Although only slightly androgenic,
women are occasionally confronted with virilization symptoms when taking
this compound. Should virilizing side effects become a concern, nandrolone
phenylpropionate should be discontinued immediately to help prevent a
permanent appearance.
Availability:
Nandrolone phenylpropionate has declined extensively as a pharmaceutical
product. Given its short action, and the limited use of its longer-acting
cousin nandrolone decanoate in clinical medicine, there are very few (if
any) unique applications remaining for this drug. Thus, there is little
justification for its continued production.
Brand name Durabolin appears to be unavailable in all markets worldwide.
A small number of generic and brand name products remain in less
regulated markets (mainly in Asia), due to continued demand by athletes
and bodybuilders.
Superanabolon from Spofa in the Czech Republic is also still in
manufacture. It contains only 25 mg of steroid per 1 mL ampule, which
makes it in relatively low demand among athletes.
Iran
Hormone
(Iran)
makes
a
25
mg/mL
generic
nandrolone
phenylpropionate in 1 mL ampules. Counterfeits are not known to be a
problem.