epitiostanol epitiostanol epitiostanol, sold under the brand name thiodrol, is an injected antiestrogen and anabolic–androgenic steroid (aas) of the dihydrotestosterone (dht) group which was described in the literature in 1965 and has been marketed in japan as an antineoplastic agent for the treatment of breast cancer since 1977. epitiostanolclinical datatrade namesthiodrolother namesepithiostanol; epithioandrostanol; 10275-s; 2α,3α-epithio-5α-androstan-17β-ol; 2α,3α-epithio-4,5α-dihydrotestosterone; 2α,3α-epithio-dhtroutes ofadministrationintramuscular injectiondrug classandrogen; anabolic steroid; antiestrogenidentifiers iupac name (1s,3as,3br,5as,6as,7ar,8as,8bs,10as)-8a,10a-dimethylhexadecahydro-1h-cyclopentaphenanthrothiiren-1-ol cas number2363-58-8 ypubchem cid3243chemspider391989uniiye7586973lcomptox dashboard (epa)dtxsid2045367 chemical and physical dataformulac19h30osmolar mass306.51 g·mol−13d model (jsmol)interactive image smiles cc12ccc3c(c1ccc2o)ccc4c3(cc5c(c4)s5)c inchi inchi=inchi=1s/c19h30os/c1-18-8-7-14-12(13(18)5-6-17(18)20)4-3-11-9-15-16(21-15)10-19(11,14)2/h11-17,20h,3-10h2,1-2h3key:obmlhupnrurlok-uhfffaoysa-n medical uses epitiostanol is used as an antiestrogen and antineoplastic agent in the treatment of breast cancer. it has also been found to be effective in the treatment of gynecomastia. side effects