5α-dihydronandrolone 5α-dihydronandrolone 5α-dihydronandrolone (also known as 5α-dhn, dihydronandrolone, dhn, 5α-dihydro-19-nortestosterone, or 5α-estran-17β-ol-3-one) is a naturally occurring anabolic–androgenic steroid (aas) and a 5α-reduced derivative of nandrolone (19-nortestosterone). it is a major metabolite of nandrolone and is formed from it by the actions of the enzyme 5α-reductase analogously to the formation of dihydrotestosterone (dht) from testosterone. 5α-dihydronandroloneclinical dataother namesdihydronandrolone; dhn; 5α-dhn; 5α-dihydro-19-nortestosterone; 5α-estran-17β-ol-3-one; 19-nor-5α-androstan-17β-ol-3-oneidentifiers iupac name (5s,8r,9r,10s,13s,14s,17s)-17-hydroxy-13-methyl-2,4,5,6,7,8,9,10,11,12,14,15,16,17-tetradecahydro-1h-cyclopentaphenanthren-3-one cas number1434-85-1pubchem cid94202chemspider85015uniii0v6o3097qchemblchembl3137999comptox dashboard (epa)dtxsid60931866 chemical and physical dataformulac18h28o2molar mass276.420 g·mol−13d model (jsmol)interactive image smiles c12cc3(1cc2o)cc43ccc(=o)c4 inchi inchi=1s/c18h28o2/c1-18-9-8-14-13-5-3-12(19)10-11(13)2-4-15(14)16(18)6-7-17(18)20/h11,13-17,20h,2-10h2,1h3/t11-,13-,14+,15+,16-,17-,18-/m0/s1key:rhvbiejvjwnxbu-pnokgrbdsa-n when testosterone is 5α-reduced into dht, which is a much more potent aas in comparison, its effects are potentiated on a local level. the tissues in which this occurs (i.e., the tissues that express 5α-reductase) are referred to as "androgenic" tissues and include the skin, hair follicles, and prostate gland, among others. the conversion of testosterone into dht is an important factor in the etiology of a variety of androgen-dependent conditions, including acne, excessive facial/body hair growth, scalp hair loss, prostate enlargement, and prostate cancer. unlike the case of testosterone and dht, 5α-dhn is a much weaker agonist of the androgen receptor (ar) than is nandrolone. for this reason, instead of local potentiation in androgenic tissues, there is a local inactivation when nandrolone is converted into 5α-dhn by 5α-reductase in these tissues. this is thought to be largely or completely responsible for the exceptionally high ratio of anabolic to androgenic effects seen with nandrolone. the combination of nandrolone with a 5α-reductase inhibitor like finasteride or dutasteride will block the conversion of nandrolone into 5α-dhn and, unlike with testosterone and various other aas, thereby considerably increase the propensity of nandrolone for producing androgenic side effects. relative affinities of nandrolone and related steroids at the androgen receptor compoundrar (%)har (%) testosterone3838 5α-dihydrotestosterone77100 nandrolone7592 5α-dihydronandrolone3550 ethylestrenolnd2 norethandrolonend22 5α-dihydronorethandrolonend14 metribolone100110 sources: see template.