EPITESTOSTERONE
From DrugPedia: A Wikipedia for Drug discovery
Epitestosterone Pubchem(10204)
The 17-alpha isomer of TESTOSTERONE, derived from PREGNENOLONE via the delta5-steroid pathway, and via 5-androstene-3-beta,17-alpha-diol. Epitestosterone acts as an antiandrogen in various target tissues. The ratio between testosterone/epitestosterone is used to monitor anabolic drug abuse.
| MMDB ID | PDB ID | Reference |
|---|---|---|
| 46914 | 2IPF | Faucher F, Cantin L, Pereira de Je, Lemieux M, Luu-The V, Labrie F, Breton RMouse 17alpha-hydroxysteroid dehydrogenase (AKR1C21) binds steroids differently from other aldo-keto reductases: identification and characterization of amino acid residues critical for substrate bindingJ. Mol. Biol. v369, p.525-540 |
| 46915 | 2IPG | Faucher F, Cantin L, Pereira de Je, Lemieux M, Luu-The V, Labrie F, Breton RMouse 17alpha-hydroxysteroid dehydrogenase (AKR1C21) binds steroids differently from other aldo-keto reductases: identification and characterization of amino acid residues critical for substrate bindingJ. Mol. Biol. v369, p.525-540 |
| 46916 | 2IPJ | Faucher F, Cantin L, Pereira de Je, Lemieux M, Luu-The V, Labrie F, Breton RMouse 17alpha-hydroxysteroid dehydrogenase (AKR1C21) binds steroids differently from other aldo-keto reductases: identification and characterization of amino acid residues critical for substrate bindingJ. Mol. Biol. v369, p.525-540 |
Epitestosterone is a natural steroid, an inactive epimer of the hormone testosterone. Structurally, it differs from testosterone only in the configuration at the OH-bearing carbon, C17. Epitestosterone is believed to form in a similar way to testosterone; a 1993 study found that around 50% of epitestosterone production in human males can be ascribed to the testis,<ref> Template:Cite news</ref> although the exact pathway of its formation is still the subject of research. It has been shown to accumulate in mammary cyst fluid and in the prostate.<ref>Template:Cite news</ref> Epitestosterone levels are typically highest in young males; however, by adulthood, most healthy males exhibit a testosterone to epitestosterone ratio (T/E ratio) of about 1:1.<ref> Template:Cite news</ref>
[edit] Epitestosterone and testosterone
It has been shown that exogenous administration of testosterone does not affect levels of epitestosterone in the body. As a result, tests to determine the ratio of testosterone to epitestosterone in urine are used to find athletes who are doping.<ref> Template:Cite news</ref> Most persons have a ratio of about 1:1 testosterone to epitestosterone (T/E ratio) in their urine. However, it is not uncommon to find T/E ratios of up to 4:1 and even T/E ratios of 10:1 can be normal for some individuals. T/E tests are most common because a person may naturally have high levels of testosterone, but even so average T/E ratios for the population in general tends close to 1:1.
Epitestosterone has not been shown to enhance athletic performance, although administration of epistestosterone can be used to mask a high level of testosterone if the standard T/E ratio test is used. As such, epitestosterone is banned by many sporting authorities as a masking agent for testosterone.
In 1996 the US athlete Mary Decker failed a T/E test with a T/E ratio of greater than 6, the limit in force at the time. She took the case to arbitration, arguing that birth control pills can cause false positives for the test, but the arbitration panel ruled against her.
On September 20, 2007 Floyd Landis was stripped of his title as winner of the Tour de France, and was subjected to a two year ban from professional racing after a second test showing an elevated T/E ratio. Test results from Floyd Landis' "A" test sample indicated that while the ratio was 11:1, his testosterone level was in the normal range and the problem was actually a deficient level of epitestosterone<ref>This is unsubstantiated. Reference is needed</ref>. Landis won the 17th stage of the tour; however, tests taken immediately after the stage victory showed a T/E ratio of 11:1<ref>This is disputed. According to testimony offered in the USADA hearing, multiple test of the same sample produced results ranging from 4:1 up to 11:1. The lab chose to report the 11:1 figure.</ref>, more than double the 4:1 imposed limit (recently lowered from prior limits of 8:1 and 6:1). On August 1, 2006, media reports said that synthetic testosterone had been detected in the A sample, using the carbon isotope ratio test CIR. The presence of synthetic testosterone means that some of the testosterone in Landis’s body came from an external source and was not naturally produced by his own system. These results conflict with Landis's public speculation that it was a natural occurrence.<ref>Template:Cite news</ref> Landis had emphatically denied the charge, pointing out the scientific data that testosterone cannot enhance athletic performance unless taken over an extended period of time with regular doses.
