Metenolone acetate, or methenolone acetate, sold under the brand names Primobolan and Nibal, is an androgen and anabolic steroid (AAS) medication which is used mainly in the treatment of anemia due to bone marrow failure. It is taken by mouth. Although it was widely used in the past, the drug has mostly been discontinued and hence is now mostly no longer available. A related drug, metenolone enanthate, is given by injection into muscle.

Side effects of metenolone acetate include symptoms of masculinization like acne, increased hair growth, voice changes, and increased sexual desire. The drug is a synthetic androgen and anabolic steroid and hence is an agonist of the androgen receptor (AR), the biological target of androgens like testosterone and dihydrotestosterone (DHT). It has moderate anabolic effects and weak androgenic effects, as well as no estrogenic effects or risk of liver damage. Metenolone enanthate is a metenolone ester and a prodrug of metenolone in the body.

Metenolone acetate was introduced for medical use in 1961. In addition to its medical use, metenolone acetate is used to improve physique and performance. The drug is a controlled substance in many countries and so non-medical use is generally illicit. It remains marketed for medical use only in a few countries, such as Japan and Moldova.

Side effects

Pharmacology

vte Androgenic vs. anabolic activity ratioof androgens/anabolic steroids
MedicationRatioa
Testosterone~1:1
Androstanolone (DHT)~1:1
Methyltestosterone~1:1
Methandriol~1:1
Fluoxymesterone1:1–1:15
Metandienone1:1–1:8
Drostanolone1:3–1:4
Metenolone1:2–1:3
Oxymetholone1:2–1:9
Oxandrolone1:13–1:3
Stanozolol1:1–1:3
Nandrolone1:3–1:16
Ethylestrenol1:2–1:19
Norethandrolone1:1–1:2
Notes: In rodents. Footnotes: a = Ratio of androgenic to anabolic activity. Sources: See template.
vte Parenteral durations of androgens/anabolic steroids
MedicationFormMajor brand namesDuration
TestosteroneAqueous suspensionAndronaq, Sterotate, Virosterone2–3 days
Testosterone propionateOil solutionAndroteston, Perandren, Testoviron3–4 days
Testosterone phenylpropionateOil solutionTestolent8 days
Testosterone isobutyrateAqueous suspensionAgovirin Depot, Perandren M14 days
Mixed testosterone estersaOil solutionTriolandren10–20 days
Mixed testosterone estersbOil solutionTestosid Depot14–20 days
Testosterone enanthateOil solutionDelatestryl14–28 days
Testosterone cypionateOil solutionDepovirin14–28 days
Mixed testosterone esterscOil solutionSustanon 25028 days
Testosterone undecanoateOil solutionAveed, Nebido100 days
Testosterone buciclatedAqueous suspension20 Aet-1, CDB-1781e90–120 days
Nandrolone phenylpropionateOil solutionDurabolin10 days
Nandrolone decanoateOil solutionDeca Durabolin21–28 days
MethandriolAqueous suspensionNotandron, Protandren8 days
Methandriol bisenanthoyl acetateOil solutionNotandron Depot16 days
Metenolone acetateOil solutionPrimobolan3 days
Metenolone enanthateOil solutionPrimobolan Depot14 days
Note: All are via i.m. injection. Footnotes: a = TP, TV, and TUe. b = TP and TKL. c = TP, TPP, TiCa, and TD. d = Studied but never marketed. e = Developmental code names. Sources: See template.

Chemistry

Metenolone acetate, or metenolone 17β-acetate, is a synthetic androstane steroid and a derivative of DHT. It is the C17β acetate ester of metenolone, which itself is 1-methyl-δ1-4,5α-dihydrotestosterone (1-methyl-δ1-DHT) or 1-methyl-5α-androst-1-en-17β-ol-3-one.

vte Structural properties of major anabolic steroid esters
Anabolic steroidStructureEsterRelative mol. weightRelative AAS contentbDurationc
PositionMoietyTypeLengtha
Boldenone undecylenateC17βUndecylenic acidStraight-chain fatty acid111.580.63Long
Drostanolone propionateC17βPropanoic acidStraight-chain fatty acid31.180.84Short
Metenolone acetateC17βEthanoic acidStraight-chain fatty acid21.140.88Short
Metenolone enanthateC17βHeptanoic acidStraight-chain fatty acid71.370.73Long
Nandrolone decanoateC17βDecanoic acidStraight-chain fatty acid101.560.64Long
Nandrolone phenylpropionateC17βPhenylpropanoic acidAromatic fatty acid– (~6–7)1.480.67Long
Trenbolone acetateC17βEthanoic acidStraight-chain fatty acid21.160.87Short
Trenbolone enanthatedC17βHeptanoic acidStraight-chain fatty acid71.410.71Long
Footnotes: a = Length of ester in carbon atoms for straight-chain fatty acids or approximate length of ester in carbon atoms for aromatic fatty acids. b = Relative androgen/anabolic steroid content by weight (i.e., relative androgenic/anabolic potency). c = Duration by intramuscular or subcutaneous injection in oil solution. d = Never marketed. Sources: See individual articles.

History

Metenolone acetate was first introduced for medical use in West Germany in 1961 under the brand name Primobolan and in the United States in 1962.

Society and culture

Generic names

Metenolone acetate is the generic name of the drug and its INNTooltip International Nonproprietary Name, while methenolone acetate is its USANTooltip United States Adopted Name and BANMTooltip British Approved Name.

Brand names

Metenolone acetate is or has been marketed under a number of brand names including Primobolan, Primobolan S, Primonabol, and Nibal.

Availability

Metenolone acetate is marketed in Japan and Moldova.