Epitestosterone

Epitestosterone

Names
IUPAC name (8R,9S,10R,13S,14S,17R)-17-hydroxy-10,13-dimethyl-1,2,6,7,8,9,11,12,14,15,16,17-dodecahydrocyclopenta[a]phenanthren-3-one
Other names Isotestosterone; 17α-Testosterone; Androst-4-en-17α-ol-3-one; 17α-Hydroxyandrost-4-en-3-one
Identifiers
CAS Number	481-30-1 N
3D model (Jmol)	Interactive image
ChEBI	CHEBI:42534 N
ChEMBL	ChEMBL196228 Y
ChemSpider	9789 Y
DrugBank	DB07768 Y
ECHA InfoCard	100.169.813
PubChem	10204
UNII	48L726977Z
InChI InChI=1S/C19H28O2/c1-18-9-7-13(20)11-12(18)3-4-14-15-5-6-17(21)19(15,2)10-8-16(14)18/h11,14-17,21H,3-10H2,1-2H3/t14-,15-,16-,17+,18-,19-/m0/s1 Key: MUMGGOZAMZWBJJ-KZYORJDKSA-N
SMILES C[C@]12CC[C@H]3[C@H]([C@@H]1CC[C@H]2O)CCC4=CC(=O)CC[C@]34C
Properties
Chemical formula	C19H28O2
Molar mass	288.431 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Epitestosterone, or isotestosterone, also known as 17α-testosterone or as androst-4-en-17α-ol-3-one, is an endogenous steroid and an epimer of the androgen sex hormone testosterone. It is a weak competitive antagonist of the androgen receptor (AR) and a potent 5α-reductase inhibitor.

Structurally, epitestosterone differs from testosterone only in the configuration at the hydroxy-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, 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. 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.

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. A study of Australian athletes found that the mean T/E ratio in the study was 1.15:1. Another study found that the max T/E ratio for the 95th percentile of athletes was 3.71:1, and the max T/E ratio for the 99th percentile was 5.25:1

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.