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Clinical data
Trade namesMyagen, Methosarb
Other namesU-19763; NSC-66233; 7α,17α-Dimethyltestosterone; 7α,17α-Dimethylandrost-4-en-17β-ol-3-one
Routes of
By mouth
  • (7R,8R,9S,10R,13S,14S,17S)-17-hydroxy-7,10,13,17-tetramethyl-2,6,7,8,9,11,12,14,15,16-decahydro-1H-cyclopenta[a]phenanthren-3-one
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.015.018 Edit this at Wikidata
Chemical and physical data
Molar mass316.485 g·mol−1
3D model (JSmol)
  • O=C4\C=C3/[C@]([C@H]2CC[C@]1([C@@H](CC[C@@]1(O)C)[C@@H]2[C@H](C)C3)C)(C)CC4
  • InChI=1S/C21H32O2/c1-13-11-14-12-15(22)5-8-19(14,2)16-6-9-20(3)17(18(13)16)7-10-21(20,4)23/h12-13,16-18,23H,5-11H2,1-4H3/t13-,16+,17+,18-,19+,20+,21+/m1/s1

Bolasterone (INN, USAN) (brand names Myagen, Methosarb; former developmental code name U-19763), also known as 7α,17α-dimethyltestosterone, is a 17α-alkylated androgen/anabolic steroid (AAS) which is used in veterinary medicine.[1][2] It has close structural similarity to testosterone, and like methyltestosterone has a methyl group at C17α in order to increase oral bioavailability.[1] In addition, it is also 7α-methylated, similar to its 7β-methylated isomer calusterone.[1] The medication has a low to moderate ratio of anabolic to androgenic activity, similar to that of fluoxymesterone.[3]

Bolasterone is on the World Anti-Doping Agency's list of prohibited substances,[4] and is therefore banned from use in most major sports.


  1. ^ a b c Elks J (14 November 2014). The Dictionary of Drugs: Chemical Data: Chemical Data, Structures and Bibliographies. Springer. pp. 646–. ISBN 978-1-4757-2085-3.
  2. ^ Morton IK, Hall JS (6 December 2012). Concise Dictionary of Pharmacological Agents: Properties and Synonyms. Springer Science & Business Media. pp. 52–. ISBN 978-94-011-4439-1.
  3. ^ Kochakian CD (6 December 2012). Anabolic-Androgenic Steroids. Springer Science & Business Media. pp. 377, 401. ISBN 978-3-642-66353-6.
  4. ^ "The World Anti-Doping Code: The 2020 Prohibited List" (PDF). World Anti-Doping Agency. Retrieved 2019-12-28.