Chemical Names 19-norandrost-4-en-3-one-17beta-ol, 17beta-hydroxy-estr-4-en-3-one
Estrogenic Activity low
Progestational Activity moderate
Durabolin is a trade name for nandrolone phenylpropionate, 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.
Nandrolone phenylpropionate was first described in 1957.471 It became a 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.
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.
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.
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.
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.
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.
Nandrolone phenylpropionate (in oil) can be positively identified using ROIDTEST™ Substance Tests A & D. Following recent market trends, we find that black market preparations labeled as nandrolone phenylpropionate have a moderate to high risk of containing no or substitute steroid ingredients.
471. Overbeek G A, J. de Visser: Acta endocrin. (Kbh.) 24 (1957):209.
472. Biosynthesis of Estrogens, Gual C, Morato T, Hayano M, Gut M and Dorfman R. Endocrinology 71 (1962):920-25.
473. Aromatization of androstenedione and 19-nortestosterone in human placental, liver and adipose tissues (abstract). Nippon Naibunpi Gakkai Zasshi
474. Competitive progesterone antagonists: receptor binding and biologic activity of testosterone and 19-nortestosterone derivatives. Reel JR, Humphrey RR, Shih YH, Windsor BL, Sakowski R, Creger PL, Edgren RA. Fertil Steril 31(5) May (1979):552-61.
475. Studies of the biological activity of certain 19-nor steroids in female animals. Pincus G, Chang M, Zarrow M, Hafez E, Merrill A. December 1956.
476. Different Pattern of Metabolism Determine the Relative Anabolic Activity of 19-Norandrogens. J Steroid Biochem Mol Bio 53 (1995):255-7.
477. Relative binding affinities of testosterone, 19-nortestosterone and the 5-alpha reduced derivatives to the androgen receptor. Toth M, Zakar T. J Steroid Biochem 17 (1982):653-60.
478. Metabolic effects of nandrolone decanoate and resistance training in men with HIV. Sattler FR, Schroeder ET, Dube MP, Jaque SV, Martinez C, Blanche PJ, Azen S, Krauss RM. Am J Physiol Endocrinol Metab. 283(6) Dec (2002):E1214-22. Epub 2002 Aug 27.
479. Lipemic and lipoproteinemic effects of natural and synthetic androgens in humans. Crist DM, Peake GT, Stackpole PJ. Clin Exp Pharmacol Physiol
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480. Influence of nandrolonedecanoate on the pituitary-gonadal axis in males. Bijlsma J,Duursma S,Thijssen J,Huber O.Acta Endocrinol 101 (1982):108- 12.