Chemical Names 17beta-Hydroxy-1-methyl-5alpha-androst-1-en-3-one, 1-methyl-1(5-alpha)-androsten-3-one-17b-ol
Estrogenic Activity none
Progestational Activity no data available (low)
Primobolan Depot is an injectable version of the steroid methenolone. This is the same constituent in Primobolan® orals (methenolone acetate), although here an enanthate ester is used to slow the steroid’s release from a site of injection. Methenolone enanthate offers a similar pattern of steroid release as testosterone enanthate, with blood hormone levels remaining markedly elevated for approximately 2 weeks. Methenolone itself is a moderately strong anabolic steroid with very low androgenic properties. Its anabolic effect is considered to be slightly less than Deca-Durabolin® (nandrolone decanoate) on a milligram for milligram basis. Methenolone enanthate is most commonly used during cutting cycles, when lean mass gain, not a raw mass increase, is the main objective.
Methenolone was first described in 1960.567 Squibb introduced the drug (as methenolone enanthate) to the U.S. prescription drug market in 1962,568 sold for a very short time in the U.S. under the brand name of Nibal® Depot. Rights to the drug were given to Schering in West Germany (now Bayer) that same year, and Nibal® Depot soon disappeared from the U.S. market. Schering would sell methenolone enanthate under its new and ultimately most recognizable brand name, Primobolan® Depot. During the 1960s and ’70’s Primobolan Depot was available mainly in Europe, including such countries as Switzerland, Italy, Germany, Austria, Belgium, France, Portugal, and Greece.
Schering maintained patent control over methenolone enanthate until the late 1970s. Before its patents expired, Schering had rigorously protected its intellectual property rights against any potential infringement, even in the U.S. market, where the company had not been marketing Primobolan Depot. Although methenolone enanthate has not been available for commercial sale in the United States for decades, it has technically retained its status as an FDA-approved drug.
Primobolan Depot is typically prescribed as a lean tissue building anabolic agent, often used in cases where body wasting has occurred secondary to an operation, prolonged infection, wasting disease, aggressive corticosteroid administration, or convalescence. Some clinicians also prescribe this agent for treating osteoporosis, sarcopenia (the natural loss of muscle mass with aging), certain cases of chronic hepatitis, and breast carcinoma (usually as a secondary medication following other therapies). The steroid has also been used to promote weight gain in underweight premature infants and children in clinical studies, and was able to do so effectively and without signs of toxicity or undesirable effects.569 Athletes have long favored the combined strong anabolic, weak androgenic, and non-estrogenic nature of this drug, which makes it very desirable for building lean muscularity without side effects.
Although Primobolan Depot demonstrated a good record of clinical safety, by the 1990s Schering had grown to be a multinational pharmaceutical giant, and was inevitably forced to reexamine its global steroid offerings in light of public concerns about sports doping. Primobolan Depot would be voluntarily withdrawn from most of the countries that had originally sold it. Today, the brand is sold in just a handful of countries including Spain, Turkey, Japan, Paraguay, and Ecuador. In spite of its limited supply, Bayer has remained (nearly) the exclusive producer of methenolone enanthate in the human drug business worldwide. In recent years, however, methenolone enanthate has shown up in a small number of other preparations, most from underground or export-only companies.
All forms of Bayer Primobolan Depot are packaged in 1 mL glass ampules and contain 100 mg of methenolone enanthate. Composition and dosage of other brands may vary by country and manufacturer.
Methenolone is a derivative of dihydrotestosterone. It contains one additional double bond between carbons 1 and 2, which helps to stabilize the 3-keto group and increase the steroid’s anabolic properties, and an additional 1-methyl group, which gives the steroid some protection against hepatic metabolism. Primobolan Depot makes use of methenolone with a carboxylic acid ester (enanthoic acid) 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) methenolone. 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.
Side Effects (Estrogenic):
Methenolone is not aromatized by the body,570 and is not measurably estrogenic. Estrogen-linked side effects should not be seen when administering this steroid. Sensitive individuals need not worry about developing gynecomastia, nor should they be noticing any appreciable water retention with this drug. The increase seen with methenolone should be quality muscle mass, not the smooth bulk that often accompanies steroids open to aromatization. During a cycle, the user should additionally not notice strong elevations in blood pressure, as this effect is also related (generally) to estrogen and water retention. Methenolone is a steroid most favored during cutting phases of training, when water and fat retention are major concerns, and sheer mass not the central objective.
Side Effects (Androgenic):
Although classified as an anabolic steroid, androgenic side effects are still possible with this substance. 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. Methenolone is still a very mild steroid, however, and strong androgenic side effects are typically related to higher doses. Women often find this preparation an acceptable choice, observing it to be a very comfortable and effective anabolic.
Side Effects (Hepatotoxicity):
Methenolone is not considered a hepatotoxic steroid; liver toxicity is unlikely. Studies have failed to produce appreciable changes in markers of hepatic stress when the drug was given in therapeutic levels.571
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. Methenolone should have a stronger negative effect on the hepatic management of cholesterol than testosterone or nandrolone due to its non-aromatizable nature, but a much weaker impact than c-17 alpha alkylated steroids. 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.
Side Effects (Testosterone Suppression):
All anabolic/androgenic steroids when taken in doses sufficient to promote muscle gain are expected to suppress endogenous testosterone production. Without the intervention of testosterone-stimulating substances, testosterone levels should return to normal within 1-4 months of drug secession. Note that prolonged hypogonadotrophic hypogonadism can develop secondary to steroid abuse, necessitating medical intervention. At a moderate dosage of 100-200 mg weekly, methenolone should offer measurably less testosterone suppression than an equal dose of nandrolone or testosterone, due to its non-aromatizable nature. If used for less than eight weeks, hormonal recovery should not be a protracted experience.
The above side effects are not inclusive. For more detailed discussion of potential side effects, see the Steroid Side Effects page.
The prescribing guidelines for Primobolan Depot recommend a maximum dosage of 200 mg at the onset of therapy, and a continuing dosage of 100 mg every week. Prolonged administration protocols generally call for a 100 mg dosage every 1-2 weeks, or 200 mg every 2-3 weeks. The usual administration protocols among male athletes call for a 200-400 mg per week dosage, which is taken for 6 to 12 weeks, which is sufficient to promote very noticeable increases in lean muscle tissue. It is, however, not unusual to see the drug taken in doses as high as 600 mg per week or more, although such amounts are likely to highlight a more androgenic side of methenolone, as well as exacerbate its negative effects on serum lipids.
Methenolone enanthate is often stacked with other (typically stronger) steroids in order to obtain a faster and more enhanced effect. During a dieting or cutting phase, a non-aromatizing androgen like Halotestin® or trenbolone can be added. The stronger androgenic component here should help to bring about an added density and hardness to the muscles. On the other hand, one might add another mild anabolic steroid such as stanozolol. The result of such a combination should again be a notable increase in muscle mass and hardness, which still should not be accompanied by greatly increased side effects. Methenolone enanthate is also used effectively during bulking phases of training. In such a scenario, the addition of testosterone or boldenone would prove quite effective for adding new muscle mass without presenting any notable hepatotoxicity to the user.
The prescribing guidelines for Primobolan Depot do not offer separate dosing recommendations for women, although it was indicated that women who were pregnant, or may become pregnant, should not use the drug. Female athletes generally respond well to a dosage of 50-100 mg per week. If both oral and injectable versions are available, the oral is often given preference, as it allows for greater control over blood hormone levels. Additionally, some women choose to include Winstrol® Depot (25 mg twice per week) or Oxandrolone (7.5-10 mg daily), and with it receive a greatly enhanced anabolic effect. Androgenic activity can be a concern with such dosing, however, and should be monitored closely. If stacking, it would be best to use a much lower starting dosage for each drug than if they were to be used alone. This is especially good advice if you are unfamiliar with the effect such a combination may have on you. A popular recommendation would also be to first experiment by stacking with oral Primobolan®, and later venture into the injectable if this is still necessary.
Pharmaceutical preparations containing methenolone enanthate remain scarce. The bulk of the supply for this compound comes from underground steroid manufacturers.
Methenolone enanthate (in oil) can be positively identified with ROIDTEST™ Substance Tests B & D. Following recent market trends, we find that black market preparations labeled as methenolone enanthate have a high risk of containing no or substitute steroid ingredients. This is likely due to the very high cost of methenolone enanthate as a raw material, which is among the most expensive of the common AAS compounds.
567. Wiechert R.et al.Chem Ber. 93 (1960):1710.
568. Methenolone enanthate, Summary of information for clinical investigators, New Brunswick, NJ. The Squibb Institute for Medical Research, April 15,
569. Anabolic effects of methenolone enanthate and methenolone acetate in underweight premature infants and children. New York State Journal of Medicine March 1, 1965, 645-8.
570. Proc. Intern. Congr. Hormonal Steroids, Milan, 1962. Excerpta Med. Intern. Congr. Ser No. 51, p. 209. Excerpta. Med. Found., Amsterdam, 1962.
571. Failure of non-17-alkylated anabolic steroids to produce abnormal liver function tests. J Clin Endocrinol Metab. 1964 Dec;24:1334-6.