Dynabolon — nandrolone undecanoate

Nandrolone undecanoate is an injectable form of the anabolic steroid nandrolone. The ester applied here is one carbon atom longer than decanoate, and consequently forms a very slightly longer-lasting drug deposit at the site of injection. With proper attention paid to carrier, concentration, volume, and pharmacokinetics, it would likely even be possible to formulate this steroid into a very long-acting drug preparation, one similar totestosterone undecanoate (Nebido) in appearance. Even without a further protracted therapeutic window, nandrolone undecanoate can be comfortably injected once every 1 to 2 weeks, which reflects its slow-acting nature. Although no longer available, this agent was once highly favored by athletes and bodybuilders for its ability to promote slow steady gains in lean mass with minimal estrogenic or androgenic side effects.

Brand name Dynabolon, Nandrolone undecanoate, Psychobolan
Androgenic 37
Anabolic 125
Standard testosterone
Chemical Names 19-norandrost-4-en-3-one-17beta-ol
Estrogenic Activity low
Progestational Activity moderate

History of Nandrolone Undecanoate

Nandrolone undecanoate was developed during the 1960’s, and was subsequently sold as Dynabolon in Italy (Chrinos) and France (Theramex), and as Psychobolan in Germany (Theramex). The Italian product was moved to the new Farmasister label years later, but retained the original Dynabolon trade name. Dynabolon was generally indicated for use in patients suffering from malnutrition, catabolic states, or recovering from major surgery. It was also used to combat osteoporosis, including the treatment of androgen-sensitive populations such as women and the elderly. Nandrolone undecanoate seems to have exhibited a fair safety record, yet in spite of this, the three known commercial preparations did not last on their respective prescription drug markets. Psychobolan from Germany and Dynabolon from Farmasister in Italy were discontinued many years ago, and Dynabolon from France finally followed before the close of the 1990’s. Presently, no legitimate pharmaceutical preparation containing nandrolone undecanoate is known to exist.

How is Nandrolone Undecanoate Supplied

Nandrolone undecanoate is no longer available as a prescription drug product. When manufactured, it was supplied at a concentration of 80.5 mg/mL dissolved in oil and sealed in a 1 mL ampule. Each ampule provided the equivalent of 50 mg of nandrolone base.

Structural Characteristics of Nandrolone Undecanoate

Nandrolone undecanoate is a modified form of nandrolone, where a carboxylic acid ester (undecanoic acid) 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 undecanoate is designed to provide a slow release of nandrolone for up to 3 to 4 weeks following injection.

Nandrolone Undecanoate Side Effects (Estrogenic)

Nandrolone has a low tendency for estrogen conversion, estimated to be only about 20% of that seen with testosterone. 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. Consequently, estrogenrelated 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. 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. 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.

Nandrolone Undecanoate 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). 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.

Nandrolone Undecanoate Side Effects (Hepatotoxicity)

Nandrolone is not c-17 alpha alkylated, and not known to have hepatotoxic effects. Liver toxicity is unlikely.

Nandrolone Undecanoate 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. 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. Nandrolone injectables, however, should still have a significantly weaker impact on serum lipids than c-17 alpha alkylated agents. Anabolic/androgenic steroids may also adversely affect 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.

Nandrolone Undecanoate Side Effects (Testosterone Suppression)

All anabolic/androgenic steroids when taken in doses sufficient to promote muscle gain are expected to suppress endogenous testosterone production. For sake of comparison, studies administering 100 mg per week of nandrolone decanoate for 6 weeks have demonstrated an approximate 57% reduction in serum testosterone levels during therapy. At a dosage of 300 mg per week, this reduction reached 70%. 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. 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.

Nandrolone Undecanoate Administration (Men)

Nandrolone undecanoate was used clinically at a dose of 1 ampule every 1 to 2 weeks. A total of 3 to 6 ampules were used for a given 6-week period of therapy.

When used for physique- or performance-enhancing purposes, a dose of 3 to 4 ampules (241.5 to 322mg) per week is most common, 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, which should be accompanied by a low level of estrogenic and androgenic activity. Higher doses (400-600 mg per week) will impart a stronger anabolic effect, but can be difficult given the relatively low concentration this steroid was manufactured in. Instead, many opted to combine this agent with other anabolic/androgenic steroids for a stronger effect. Given its properties, it seems to fit well for both bulking and cutting purposes, and can reasonably replace Deca- in such cycles.

Nandrolone Undecanoate Administration (Women)

Nandrolone undecanoate was used clinically at a dose of 1 ampule every 1 to 2 weeks. A total of 3 to 6 ampules were used for a given 6-week period of therapy.

When used for physique- or performance-enhancing purposes, a dosage of 1 ampule (80.5 mg) every 10 days was most common, which is taken for 4 to 6 weeks. Although only slightly androgenic, women are occasionally confronted with virilization symptoms when taking this compound. Should virilizing side effects become a concern, the drug should be discontinued immediately to help prevent their permanent appearance. After a sufficient period of withdrawal, the shorter acting nandrolone Durabolin might be considered a safer (more controllable) option. This drug stays active for only several days, greatly reducing the withdrawal time if indicated.

Nandrolone Undecanoate Availability

Nandrolone undecanoate is no longer available as a prescription drug product. Some underground preparations are, however, known to exist.

Bodybuilders reference

This is a nandrolone drug with a noted higher androgenic effect than Deca. Due to this, Dynabolin was considered to be a stronger drug than Durabolin or Deca milligram for milligram. Therefore it was commonly believed to bring a quicker and larger build-up of strength and muscle mass. Gains were usually very solid and water retention was slightly higher than Deca. Dynabolin also aromatizes more than Deca so the slight increase in reported estrogenic negative side effects was not surprising. According to the available literature, Dynabolin is well tolerated by the liver well. But in some cases liver markers did charge. High blood pressure and elevated cholesterol levels can occur in some individuals due to higher dosages, but most recent research suggests nandrolones positively effect the HDL (Good) to LDL (Bad) ratio. All in all most of these possible side effects disappeared after usage stooped.

Males made fair progress with a dosage of 161-322-mg (2-4-ml) per week divided into two equal injections such as Mon. & Thurs. Based upon reports, women should not use more than 80.5 mg (1-ML) once weekly.

Some women noted virilization effects with even this dosage when the cycle lasted more than 30-42 days. Since Dynabolin is actually a shorter lasting injectable nandrolone, injections for males were administered twice weekly to maintain serum levels.

This drugs active-life falls between Durabolin and Deca in fact. This drug causes a high nitrogen retention and increases protein synthesis dramatically. So higher protein intake was a must if athletes wanted to utilize its full potential. It was rare that antiestrogen drugs were necessary when using this drug except in dosages of well over 402.5 mg weekly.

Due to low-to-moderate aromatization and high anabolic properties, this drug induced quality lean muscle tissue gains with little increase in the body's water retention extracellularly (outside of cells). The result was a reasonable lean appearance during use.

Anabolic Steroid Guide reference

Along with Anadur, Deca-Durabolin, and Durabolin, this is another steroid containing the substance nandrolone. Dynabolon is a favorite among athletes since it brings good results with few side effects. Although it is often compared to "Deca", its effect is mg per mg comparable or slightly less. The reason is that Dynabolon is slightly androgenic with an anabolic effect, thus it strongly promotes the protein synthesis. The increased androgenic component helps the athlete achieve a good strength increase and an accelerated regeneration. Those who have had good results with Deca will usually respond even better to Dynabolon. Athletes re-port a distinct, quickly effective, solid gain in muscles, which goes hand in hand with a significant gain in strength. The increase in body weight and the improved strength are the result of the water retention in tissues and joints. Dynabolon does not strongly aromatize in dosages below 4 ml/week. Dynabolon is effective for 1-2 weeks, thus requiring more frequent injections than Deca. Bodybuilders who work with this compound usually inject it twice a week. The minimum dosage is 2ml/week. A weekly dosage of 4 ml (equal to 322 mg) is usually sufficient for most athletes to achieve satisfactory results. This requires the injection of 2 ml (equal to 161 mg or 2 ampules) twice weekly. Higher dosages would certainly bring even better gains but often go hand in hand with distinct water retention. Such dosages also aromatize so strongly that antiestrogens must be taken to main-tain the quality of the muscles. Women do well with 1 ml/week and rarely show virilization symptoms if the compound is not taken for more than six weeks. Female athletes rarely use Dynabolon since they normally prefer Durabolin, which has a shorter duration of effectiveness.


Wlliam Llewellyn (2011) - Anabolics
L. Rea (2002) - Chemical Muscle Enhancement Bodybuilders Desk Reference
Anabolic Steroid Guide

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