estromustine estromustine estromustine (developmental code name leo 271 f), also known as estrone 17β-3-n-bis(2-chloroethyl)carbamate or estrone–cytostatic complex, is a major active metabolite of the cytostatic antineoplastic agent and estrogen estramustine phosphate, a medication used in the treatment of prostate cancer. not to be confused with estramustine phosphate or estramustine. estromustineclinical dataother nameseom; leo 271 f; estrone 17β-3-n-bis(2-chloroethyl)carbamate; estrone–cytostatic complexdrug classchemotherapeutic agent; estrogen; estrogen esterpharmacokinetic dataelimination half-life14 hoursidentifiers iupac name phenanthren-3-yl] n,n-bis(2-chloroethyl)carbamate cas number62899-40-5pubchem cid124946chemspider111241comptox dashboard (epa)dtxsid40978673 chemical and physical dataformulac23h29cl2no3molar mass438.39 g·mol−13d model (jsmol)interactive image smiles c12cc3(1ccc2=o)ccc4=c3c=cc(=c4)oc(=o)n(cccl)cccl inchi inchi=1s/c23h29cl2no3/c1-23-9-8-18-17-5-3-16(29-22(28)26(12-10-24)13-11-25)14-15(17)2-4-19(18)20(23)6-7-21(23)27/h3,5,14,18-20h,2,4,6-13h2,1h3/t18-,19-,20+,23+/m1/s1key:axwyrohifvwhmr-ugtoymoasa-n