mk-434 mk-434 mk-434 is a 5α-reductase inhibitor which was under development in the 1990s by merck & co for the treatment of a variety of androgen-dependent conditions including benign prostatic hyperplasia, prostate cancer, pattern hair loss, excessive hair growth, acne, and seborrhea but was never marketed. it acts as a selective inhibitor of 5α-reductase type 2. the drug has been found to decrease circulating dihydrotestosterone levels by a maximum of approximately 50% in men. mk-434 is a synthetic 4-azasteroid and is structurally related to other 5α-reductase inhibitors like finasteride. mk-434clinical dataother namesmk-0434; 17β-benzoyl-4-aza-5α-androst-1-en-3-oneroutes ofadministrationby mouthdrug class5α-reductase inhibitoridentifiers iupac name (1s,3as,3bs,5ar,9ar,9bs,11as)-1-benzoyl-9a,11a-dimethyl-1,2,3,3a,3b,4,5,5a,6,9b,10,11-dodecahydroindenoquinolin-7-one cas number134067-56-4pubchem cid131705chemspider116366uniij5dr1p0ikkchemical and physical dataformulac25h31no2molar mass377.528 g·mol−13d model (jsmol)interactive image smiles c12cc3(1cc2c(=o)c4=cc=cc=c4)cc53(c=cc(=o)n5)c inchi inchi=1s/c25h31no2/c1-24-14-12-19-17(8-11-21-25(19,2)15-13-22(27)26-21)18(24)9-10-20(24)23(28)16-6-4-3-5-7-16/h3-7,13,15,17-21h,8-12,14h2,1-2h3,(h,26,27)/t17-,18-,19-,20+,21+,24-,25+/m0/s1key:zytqeowfsvtrlx-qkongsnmsa-n