Metenolone, or methenolone, is an androgen and anabolic steroid (AAS) which is used in the form of esters such as metenolone acetate (brand name Primobolan, Nibal) and metenolone enanthate (brand name Primobolan Depot, Nibal Injection).[2][3][4][5][6] Metenolone esters are used mainly in the treatment of anemia due to bone marrow failure.[7] Metenolone acetate is taken by mouth, while metenolone enanthate is given by injection into muscle.[6]
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Trade names | Primobolan, Nibal (as metenolone acetate); Primobolan Depot, Nibal Injection (as metenolone enanthate) |
Other names | Methenolone; Methylandrostenolone; 1-Methyl-δ1-4,5α-dihydrotestosterone; 1-Methyl-δ1-DHT; 1-Methyl-5α-androst-1-en-17β-ol-3-one |
AHFS/Drugs.com | International Drug Names |
Routes of administration | By mouth (as metenolone acetate), intramuscular injection (as metenolone enanthate) |
Drug class | Androgen; Anabolic steroid |
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ECHA InfoCard | 100.005.285 |
Chemical and physical data | |
Formula | C20H30O2 |
Molar mass | 302.458 g·mol−1 |
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Side effects of metenolone esters include symptoms of masculinization like acne, increased hair growth, voice changes, and increased sexual desire.[6] Metenolone esters are synthetic androgens and anabolic steroids and hence are agonists of the androgen receptor (AR), the biological target of androgens like testosterone and dihydrotestosterone (DHT).[6][8] They have moderate anabolic effects and weak androgenic effects, as well as no estrogenic effects or risk of liver damage.[6][8] Metenolone esters are androgen esters and prodrugs of metenolone in the body.[6]
Metenolone esters were introduced for medical use in the early 1960s.[6] In addition to their medical use, metenolone esters are used to improve physique and performance.[6] The drugs are controlled substances in many countries and so non-medical use is generally illicit.[6] They have mostly been discontinued for medical use and have limited availability.[5][6]
Metenolone, as its esters, is used almost exclusively in the treatment of anemia due to bone marrow failure.[7] It has also been used to treat wasting syndromes due to major surgery, infection, long-term corticosteroid therapy, malnutrition, or other causes.[6] It has also been used to treat osteoporosis and sarcopenia, to inhibit the natural loss of muscle mass with aging, and to promote weight gain in underweight premature infants and children.[6]
Side effects of metenolone and its esters include virilization among others.[6]
Medication | Ratioa |
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Testosterone | ~1:1 |
Androstanolone (DHT) | ~1:1 |
Methyltestosterone | ~1:1 |
Methandriol | ~1:1 |
Fluoxymesterone | 1:1–1:15 |
Metandienone | 1:1–1:8 |
Drostanolone | 1:3–1:4 |
Metenolone | 1:2–1:30 |
Oxymetholone | 1:2–1:9 |
Oxandrolone | 1:3–1:13 |
Stanozolol | 1:1–1:30 |
Nandrolone | 1:3–1:16 |
Ethylestrenol | 1:2–1:19 |
Norethandrolone | 1:1–1:20 |
Notes: In rodents. Footnotes: a = Ratio of androgenic to anabolic activity. Sources: See template. |
Due to its double bond between the C1 and C2 positions, metenolone is resistant to metabolism by 3α-hydroxysteroid dehydrogenase (3α-HSD).[6] As such, unlike DHT and the closely related DHT derivatives mestanolone (17α-methyl-DHT) and mesterolone (1α-methyl-DHT), metenolone has considerable anabolic effects.[6]
Metenolone has very low affinity for human serum sex hormone-binding globulin (SHBG), about 16% of that of testosterone and 3% of that of DHT.[9]
Metenolone, also known as 1-methyl-4,5α-dihydro-δ1-testosterone (1-methyl-δ1-DHT) or as 1-methyl-5α-androst-1-en-17β-ol-3-one, is a synthetic androstane steroid and derivative of dihydrotestosterone (DHT).[2][3][6] A closely related AAS is mesterolone (1α-methyl-DHT).[2][3][6]
Metenolone is the generic name of the drug and its INN , while methenolone is its BAN .[2][3][4][5] It has also been referred to as methylandrostenolone.[3][5] This synonym should not be confused with methandrostenolone, which is another name for a different AAS known as metandienone.[10]
Metenolone and its esters are banned from use in sports governed by the World Anti-Doping Agency.[11] The NBA and NBPA also banned the use of metenolone and its esters under the Anti-Drug Program. There are known cases of doping in sports with metenolone esters by professional athletes.