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Systematic (IUPAC) name
(13S,17S)-13,17-diethyl-17-hydroxy-1,2,6,7,8,13,14,15,16,17- decahydrocyclopenta[a]phenanthren-3-one
CAS number 618903-56-3
ATC code  ?
PubChem  ?
Chemical data
Formula C21H28O2 
Mol. mass 312.46 g/mol
Synonyms Tetrahydrogestrinone, THG, The Clear
Pharmacokinetic data
Bioavailability  ?
Metabolism  ?
Half life  ?
Excretion  ?
Therapeutic considerations
Pregnancy cat.


Legal status

Schedule I(US)

Routes Oral, Intramuscular

Tetrahydrogestrinone (often referred to as THG or The Clear) is an anabolic steroid. It has affinity to the androgen receptor and the progesterone receptor, but not to the estrogen receptor.[1] The drug has been considered a designer drug, closely related to the banned anabolic steroids gestrinone and trenbolone,[2] and was banned by the Food and Drug Administration (FDA) at the end of 2003.[3]



Structure-activity relationship studies report that the potency of the drug is outstanding, surpassing, on a milligram per milligram basis, every known synthesized or commercial available anabolic steroid at the time of its development. It is a highly potent agonist for the androgen and progesterone receptors,[4] around 10 times more potent than the comparison drugs nandrolone or trenbolone, but with no estrogenic activity. It has been found to bind to the androgen receptor with similar affinity to dihydrotestosterone and produces growth of muscle tissue.[5]

Side effects

Side effects from prolonged use are likely to include infertility in both men and women, as well as other steroid side effects such as acne and hirsutism.[6] Unlike most other anabolic steroids, THG also binds with high affinity to the glucocorticoid receptor, and while this effect may cause additional weight loss, it is also likely to cause extra side effects such as immunosuppression that are not seen with most other steroids.[7]


For a time, THG was considered the drug of choice for safe and "invisible" world record breaking in athletics, being used by several high profile gold medal winners such as the sprinter Marion Jones, who resigned from her athletic career in 2007 after admitting to using THG prior to the 2000 Sydney Olympics, where she had won three gold medals.[8]

The drug was made public when the United States Anti-Doping Agency (USADA) was contacted by an anonymous athletics coach, later identified as Trevor Graham, who claimed that several top athletes were using THG and provided the USADA with a syringe containing THG, which the USADA then used to develop a test for the substance.[9]

THG was developed by Patrick Arnold, of the Bay Area Laboratory Co-operative (BALCO), an American nutritional supplement company.[10] The company manufactured the drug through palladium-charcoal catalyzed hydrogenation from gestrinone, a substance used in gynecology for treatment of endometriosis.[citation needed]

THG had been distributed to several leading athletes, including many during the BALCO scandal. Some of the higher profile athletes accused of THG usage, such as baseball superstar Barry Bonds and Olympic Gold Medalist Marion Jones, have told reporters and investigators that they did not knowingly take THG, claiming that coaches told them the substance was a flaxseed oil supplement. Bonds has since been indicted on four counts of perjury and one count of obstruction of justice for his testimony to the BALCO grand jury, while Jones admitted on October 5, 2007 that she had lied to investigators about her use of THG and has surrendered her Olympic medals to the USOC. On November 23 2007, the International Association of Athletics Federations struck all of Marion Jones' results since September 2000, including her Olympic medal-winning performances, from its record books, and recommended that the IOC formally strip her of her Olympic medals. The IAAF also recommended her Olympic relay teammates also be stripped of their medals.[11] On December 12, the IOC formally stripped Jones of all her 2000 Olympic medals.[12]


  1. ^
  2. ^ Oct.2003 FDA statement on THG
  3. ^ THG ban
  4. ^ Labrie F, Luu-The V, Calvo E, Martel C, Cloutier J, Gauthier S, Belleau P, Morissette J, Lévesque MH, Labrie C. Tetrahydrogestrinone induces a genomic signature typical of a potent anabolic steroid. Journal of Endocrinolology. 2005 Feb;184(2):427-33.
  5. ^ Jasuja R, Catlin DH, Miller A, Chang YC, Herbst KL, Starcevic B, Artaza JN, Singh R, Datta G, Sarkissian A, Chandsawangbhuwana C, Baker M, Bhasin S. Tetrahydrogestrinone is an androgenic steroid that stimulates androgen receptor-mediated, myogenic differentiation in C3H10T1/2 multipotent mesenchymal cells and promotes muscle accretion in orchidectomized male rats. Endocrinology. 2005 Oct;146(10):4472-8.
  6. ^ Death AK, McGrath KCY, Kazlauskas R, Handelsman DJ. Tetrahydrogestrinone is a Potent Androgen and Progestin. Journal of Clinical Endocrinology and Metabolism 2004; 89(5):2498-2500.
  7. ^ Friedel A, Geyer H, Kamber M, Laudenbach-Leschowsky U, Schänzer W, Thevis M, Vollmer G, Zierau O, Diel P. Tetrahydrogestrinone is a potent but unselective binding steroid and affects glucocorticoid signalling in the liver. Toxicology Letters. 2006 June 20;164(1):16-23.
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  11. ^
  12. ^ Grohmann, Karolos. "IOC strips Marion Jones' Sydney medals", Reuters, 2007-12-12. Retrieved on 2007-12-13. 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Tetrahydrogestrinone". A list of authors is available in Wikipedia.
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