Nandrolone decanoate is a nandrolone ester , or a prodrug of nandrolone .     As such, it is an androgen and anabolic steroid , or an agonist of the AR, the biological target of androgens like testosterone and DHT.     Relative to testosterone, nandrolone decanoate has enhanced anabolic effects and reduced androgenic effects.    It is considered to have strong anabolic effects but weak androgenic effects, with respective potency ratios of – and – (index value – or about an 11:1 ratio of myotrophic to androgenic effect) relative to testosterone propionate .    Along with oxandrolone (which has a ratio of about 10:1), nandrolone esters are thought to have the highest ratio of anabolic to androgenic effect of any other AAS.   For this reason, they are considered to be among the most appropriate AAS for use in women. 
Tibolone has tissue -selective estrogenic effects, with desirable effects in bone , the brain , and the vagina , and lack of undesirable action in the endometrium and breasts .  Its tissue selectivity is the result of metabolism , enzyme modulation (., of estrogen sulfatase and estrogen sulfotransferase ), and receptor modulation that vary in different target tissues, and differs mechanistically from that of selective estrogen receptor modulators (SERMs) such as tamoxifen , which produce their tissue selectivity via means of modulation of the ER.   As such, to distinguish it from SERMs, tibolone has been described as a "selective tissue estrogenic activity regulator" (STEAR),  and also as a "selective estrogen enzyme modulator" (SEEM). 
Heavy consumption of the essential amino acid lysine (as indicated in the treatment of cold sores) has allegedly shown false positives in some and was cited by American shotputter C. J. Hunter as the reason for his positive test, though in 2004 he admitted to a federal grand jury that he had injected nandrolone.  A possible cause of incorrect urine test results is the presence of metabolites from other AAS, though modern urinalysis can usually determine the exact AAS used by analyzing the ratio of the two remaining nandrolone metabolites. As a result of the numerous overturned verdicts, the testing procedure was reviewed by UK Sport . On October 5, 2007, three-time Olympic gold medalist for track and field Marion Jones admitted to use of the drug, and was sentenced to six months in jail for lying to a federal grand jury in 2000.