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| Clinical data | |
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| Trade names | Primobolan, Nibal (asmetenolone acetate); Primobolan Depot, Nibal Injection (asmetenolone 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 (asmetenolone acetate),intramuscular injection (asmetenolone enanthate) |
| Drug class | Androgen;Anabolic steroid |
| ATC code | |
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| Identifiers | |
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| ECHA InfoCard | 100.005.285 |
| Chemical and physical data | |
| Formula | C20H30O2 |
| Molar mass | 302.458 g·mol−1 |
| 3D model (JSmol) | |
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Metenolone, ormethenolone, is anandrogen andanabolic steroid (AAS) which is used in the form ofesters such asmetenolone acetate (brand namePrimobolan,Nibal) andmetenolone enanthate (brand namePrimobolan Depot,Nibal Injection).[2][3][4][5][6]Metenolone esters are used mainly in the treatment ofanemia due tobone marrow failure.[7] Metenolone acetate istaken by mouth, while metenolone enanthate is given byinjection into muscle.[6]
Side effects of metenolone esters includesymptoms ofmasculinization likeacne,increased hair growth,voice changes, and increasedsexual desire.[6] Metenolone esters aresynthetic androgens and anabolic steroids and hence areagonists of theandrogen receptor (AR), thebiological target of androgens liketestosterone anddihydrotestosterone (DHT).[6][8] They have moderateanabolic effects and weakandrogenic effects, as well as noestrogenic effects or risk ofliver damage.[6][8] Metenolone esters areandrogen esters andprodrugs 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 toimprove physique and performance.[6] The drugs arecontrolled 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 ofanemia due tobone marrow failure.[7] It has also been used to treatwasting syndromes due to majorsurgery,infection, long-termcorticosteroid therapy,malnutrition, or other causes.[6] It has also been used to treatosteoporosis andsarcopenia, to inhibit the natural loss ofmuscle mass withaging, and to promoteweight gain in underweightpremature infants and children.[6]
Side effects of metenolone and its esters includevirilization among others.[6]
| Medication | Ratioa |
|---|---|
| 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 | 1:2–1:3 |
| Oxymetholone | 1:2–1:9 |
| Oxandrolone | 1:13–1:3 |
| Stanozolol | 1:1–1:3 |
| Nandrolone | 1:3–1:16 |
| Ethylestrenol | 1:2–1:19 |
| Norethandrolone | 1:1–1:2 |
| Notes: In rodents.Footnotes:a = Ratio of androgenic to anabolic activity.Sources: See template. | |
Due to itsdouble bond between the C1 and C2 positions, metenolone is resistant tometabolism by3α-hydroxysteroid dehydrogenase (3α-HSD).[6] As such, unlike DHT and the closely related DHT derivativesmestanolone (17α-methyl-DHT) andmesterolone (1α-methyl-DHT), metenolone has considerable anabolic effects.[6]
Metenolone has very lowaffinity for human serumsex 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 asyntheticandrostanesteroid andderivative ofdihydrotestosterone (DHT).[2][3][6] A closely related AAS ismesterolone (1α-methyl-DHT).[2][3][6]
Metenolone is thegeneric name of the drug and itsINNTooltip International Nonproprietary Name, whilemethenolone is itsBANTooltip British Approved Name.[2][3][4][5] It has also been referred to asmethylandrostenolone.[3][5] This synonym should not be confused withmethandrostenolone, which is another name for a different AAS known asmetandienone.[10]
Metenolone and its esters are banned from use in sports governed by theWorld Anti-Doping Agency.[11] TheNBA andNBPA 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 byprofessionalathletes.
