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Systematic (IUPAC) name
CAS Number 1235-15-0 YesY
ATC code None
PubChem CID: 66255
ChemSpider 59638 YesY
Synonyms Norbolethone
Chemical data
Formula C21H32O2
Molecular mass 316.47758 g/mol
 YesY (what is this?)  (verify)

Norboletone[pronunciation?] (Genabol[pronunciation?]) is an anabolic steroid. It was first developed in 1966 by Wyeth Laboratories, and tested for use as an agent to encourage weight gain and for the treatment of short stature, but was never marketed commercially because of fears that it might be toxic.[1] It subsequently showed up in urine tests on athletes in competition in the early 2000s.[2]

Norboletone was found to have been brought to the market by the chemist Patrick Arnold, of the Bay Area Laboratory Co-operative (BALCO), an American nutritional supplement company. It is reputed to have been the active ingredient in the original formulation of the "undetectable" steroid formulation known as "The Clear" before being replaced by the more potent drug tetrahydrogestrinone.[3][4]

In 2002, Don Catlin, the founder and then-director of the UCLA Olympic Analytical Lab, identified norboletone for the first time in an athlete’s urine sample. In the same year, U.S. bicycle racer Tammy Thomas was caught using it and was banned from her sport.[1] The following year, Catlin identified and developed a test for tetrahydrogestrinone (THG), the second reported designer anabolic sample—a key development in the BALCO Affair.[5]

Norboletone is on the World Anti-Doping Agency's list of prohibited substances,[6] and is therefore banned from use in most major sports.


  1. ^ a b Lee, Henry K. (2006-08-04). "Inventor of 'clear' steroid gets 3 months in prison". The San Francisco Chronicle. 
  2. ^ Catlin DH, Ahrens BD, Kucherova Y (2002). "Detection of norbolethone, an anabolic steroid never marketed, in athletes' urine". Rapid Communications in Mass Spectrometry 16 (13): 1273–1275. doi:10.1002/rcm.722. PMID 12112254. 
  3. ^ "Chemist Who Created "The Clear" Sentenced" (Press release). United States Attorney for the Northern District of California. 2006-08-04. Retrieved 2007-10-08. 
  4. ^ Knight J. (2003). "Drugs bust reveals athletes' secret steroid". Nature 425 (6960): 752. doi:10.1038/425752a. 
  5. ^ "Catlin has made a career out of busting juicers". USA Today. 2007-02-28. 
  6. ^ "The World Anti-Doping Code: The 2012 Prohibited List" (PDF). World Anti-Doping Agency. Retrieved 2012-07-17.