Primobolan (Methenolone)
1 year ago

Primobolan (Methenolone)

Primobolan® is a brand name for the anabolic steroid methenolone acetate. This agent is very similar in action to Primobolan® Depot (methenolone enanthate), except here the drug is designed for oral administration instead of injection. Methenolone acetate is a non-c17-alpha-alkylated oral steroid, one of only a few commercially available oral agents that presents limited liver toxicity to the user. It is also highly favored for its properties as a moderately effective anabolic with low androgenic and no estrogenic properties. It is, likewise, commonly used during cutting phases of training, when lean tissue growth and solid muscularity, not raw bulk, are the key objectives.


Methenolone was first described in 1960. Squibb would introduce the drug (as methenolone acetate) to the United States in 1962. This agent was sold for a very short time as a 20 mg tablet, under the brand name of Nibal®. Schering in West Germany (now Bayer) would be granted rights to the drug that same year, and would sell it under the Primobolan® name. Nibal® was soon removed from the U.S. market, never to return as a commercial product. Schering now had exclusive patent rights to produce methenolone acetate, and would continue to sell the drug uninterrupted since 1962, and consumers had naturally come to identify methenolone acetate as a product of Schering. Primobolan® has always been identified as a European steroid, and during the 1960’s and ’70’s was being offered for sale in such countries as Germany, Austria, Belgium, France, the Netherlands, and Finland. At one time Schering also manufactured a 20 mg/ml oil-based injectable of methenolone acetate in limited markets (called Primobolan® Acetate), but it has been out of manufacture since 1993.

Structural Characteristics:

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 protects the steroid against hepatic metabolism. Primobolan makes use of methenolone with a carboxylic acid ester (acetic acid) attached to the 17-beta hydroxyl group to further help protect it from oxidation during oral administration. Studies have demonstrated the methenolone is an effective oral anabolic agent in both the acetate and unesterified forms.

Side Effects (Estrogenic):

Methenolone is not aromatized by the body, 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. This steroid does have some resistance to hepatic breakdown, however, and liver toxicity, failure, and death was reported in one elderly patient receiving oral methenolone acetate. Although unlikely, hepatotoxicity cannot be completely excluded, especially with very high oral doses.


•     (Oral Version is + Acetate Ester)
•     (Injectable Version is + Enanthate Ester)
•     [17beta-Hydroxy-1-methyl-5alpha-androst-1-en-3-one]
•     Molecular weight of base: 302.4558
•     Molecular weight of Acetate ester: 60.0524
•     Molecular weight of Enanthate ester: 130.1864
•     Formula: C20H30O2
•     Melting Point:
•     Manufacturer: Schering
•     Effective dose (oral): (Men)50-100mgs/day; (Women) 10-25mgs/day
•     Effective dose (injectable): (Men) 350-600mgs/week; (Women) 100mgs/week
•     Active Life: 10-14 days (injectable); 4-6hrs (oral)
•     Detection Time: 4-5 weeks
•     Anabolic/Androgenic Ratio (Range): 88:44-57