Clinical data
AHFS/ International Drug Names
  • X
Routes of
ATC code none
Legal status
Legal status
Pharmacokinetic data
Bioavailability 100% (intramuscular)
Biological half-life 48–72 hours
Excretion Urinary
Synonyms Trienolone; RU-2341; Estra-4,9,11-trien-17β-ol-3-one
CAS Number 10161-33-8 N
PubChem (CID) 25015
ChemSpider 23383 YesY
UNII P53R4420TR YesY
Chemical and physical data
Formula C18H22O2
Molar mass 270.37 g/mol
3D model (Jmol) Interactive image
 NYesY (what is this?)  (verify)

Trenbolone (INN, BAN), also known as trienolone or trienbolone,[1][2] as well as 19-nor-δ9,11-testosterone, Δ9,11-nandrolone, or estra-4,9,11-trien-17β-ol-3-one, is an anabolic-androgenic steroid (AAS) of the 19-nortestosterone group. It is used in veterinary medicine in livestock to increase muscle growth and appetite. Trenbolone is used in the form of ester prodrugs, including trenbolone acetate (brand names Revalor (in combination with estradiol), Finaplix, Finajet) and trenbolone hexahydrobenzylcarbonate (Parabolan, Hexabolan).[3][4] Although it is not available as a prescription medication for humans, trenbolone enanthate (RU-1697) is sometimes sold under the nickname Trenabol.[2]

Veterinary use

Trenbolone improves muscle mass, feed efficiency, and mineral absorption in cattle.


Mechanism of action

It has both anabolic and androgenic effects.[2] Once metabolized, the drugs have the effect of increasing ammonium ion uptake by muscles, leading to an increase in the rate of protein synthesis. It may also have the secondary effects of stimulating appetite and decreasing the rate of catabolism, as all anabolic steroids are believed to; however, catabolism likely increases significantly once the steroid is no longer taken.[5] At least one study in rats has shown trenbolone to cause gene expression of the androgen receptor at least as potent as DHT. This evidence tends to indicate trenbolone can cause an increase in male secondary sex characteristics without the need to convert to dihydrotestosterone.[6]


To increase its effective half-life, trenbolone is administered as a prodrug as an ester conjugate such as trenbolone acetate, trenbolone enanthate, or trenbolone hexahydrobenzylcarbonate (Parabolan). Plasma lipases then cleave the ester group in the bloodstream leaving free trenbolone.

Trenbolone compounds have a binding affinity for the androgen receptor five times as high as that of testosterone.[2][7][8]

Trenbolone also binds with high affinity to the progesterone receptor,[2][8][9][10] Trenbolone binds to the glucocorticoid receptor as well.[9]


Studies on metabolism are mixed, with some studies showing that it is metabolized by aromatase or 5α-reductase into estrogenic compounds such as estradiol, or into dihydrotestosterone, respectively.[11][12]

Trenbolone and 17-epitrenbolone are both excreted in urine as conjugates that can be hydrolyzed with beta-glucuronidase.[13] This implies that trenbolone leaves the body as beta-glucuronides or sulfates.


Trenbolone is an estrane (C18) steroid and is also known by the chemical name estra-4,9,11-trien-17β-ol-3-one.

Society and culture

Some bodybuilders and athletes use trenbolone for its muscle-building and otherwise performance-enhancing effects. Such use is illegal in the United States and many other countries. The DEA classifies trenbolone as a Schedule III controlled substance under the Controlled Substances Act.[14] Trenbolone is classified as a Schedule 4 drug in Canada[15] and a class C drug with no penalty for personal use or possession in the United Kingdom.[16] Use or possession of steroids without a prescription is a crime in Australia.[17]

See also


  1. Food and Agriculture Organization of the United Nations (1990). Residues of Some Veterinary Drugs in Animals and Foods: Monographs Prepared by the Thirty-Fourth Meeting of the Joint FAO/WHO Expert Committee on Food Additives, Geneva, 30 January-8 February 1989. Food & Agriculture Org. pp. 88–. ISBN 978-92-5-102933-6.
  2. 1 2 3 4 5 William Llewellyn (2011). Anabolics. Molecular Nutrition Llc. pp. 546–. ISBN 978-0-9828280-1-4.
  3. Nichols, Wade; Hutcheson, John; Streeter, Marshall; Corrigan, Mark; Nuttelman, Brandon. "Implant Strategies for Finishing Cattle using Revalor® (trenbolone acetate and estradiol), Finaplix® (trenbolone) and/or Ralgro® (zeranol)" (PDF). Merck Animal Health.
  4. Kicman, A T (2008). "Pharmacology of anabolic steroids". British Journal of Pharmacology. 154 (3): 502–521. doi:10.1038/bjp.2008.165. ISSN 0007-1188.
  6. Wilson, V. S.; Lambright, C; Ostby, J; Gray Jr, LE (2002). "In Vitro and in Vivo Effects of 17beta-Trenbolone: A Feedlot Effluent Contaminant". Toxicological Sciences. 70 (2): 202–11. doi:10.1093/toxsci/70.2.202. PMID 12441365.
  7. Beg, Tanveer; Siddique, Yasir Hasan; Afzal, Mohammad (2007). "Chromosomal Damage Induced by Androgenic Anabolic Steroids, Stanozolol and Trenbolone, in Human Lymphocytes" (PDF). Advances in Environmental Biology. 1 (1): 39–43.
  8. 1 2 C. G. Nicholas Mascie-Taylor; Lyliane Rosetta (13 January 2011). Reproduction and Adaptation: Topics in Human Reproductive Ecology. Cambridge University Press. pp. 69–. ISBN 978-1-139-49430-4.
  9. 1 2 APMIS.: Supplementum. Munksgaard. 2001. p. 5339.
  10. Kenneth W. McKerns (13 March 2013). Reproductive Processes and Contraception. Springer Science & Business Media. pp. 171–. ISBN 978-1-4684-3824-6.
  11. Yarrow, Joshua F.; McCoy, Sean C.; Borst, Stephen E. (2010). "Tissue selectivity and potential clinical applications of trenbolone (17β-hydroxyestra-4,9,11-trien-3-one): A potent anabolic steroid with reduced androgenic and estrogenic activity". Steroids. 75 (6): 377–89. doi:10.1016/j.steroids.2010.01.019. PMID 20138077.
  12. Gettys, TW; d'Occhio, MJ; Henricks, DM; Schanbacher, BD (1984). "Suppression of LH secretion by oestradiol, dihydrotestosterone and trenbolone acetate in the acutely castrated bull". The Journal of endocrinology. 100 (1): 107–12. doi:10.1677/joe.0.1000107. PMID 6361192.
  13. Schänzer, W (1996). "Metabolism of anabolic androgenic steroids". Clinical Chemistry. 42 (7): 1001–20. PMID 8674183.
  14. "Controlled Substances Act". United States Food and Drug Administration. 11 June 2009. Retrieved 17 June 2016.

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