hexestrol diphosphate hexestrol diphosphate hexestrol diphosphate (brand names cytostatin, cytostesin, pharmestrin, retalon aquosum) is a synthetic, nonsteroidal estrogen of the stilbestrol group related to diethylstilbestrol and used as an estrogen and antineoplastic agent in the treatment of prostate cancer. it is a water-soluble ester of hexestrol. the medication has been known since at least 1956. hexestrol diphosphateclinical datatrade namescytostatin, cytostesin, pharmestrin, retalon aquosumother namesda-268; nsc-35752routes ofadministrationintravenous injectiondrug classestrogen; nonsteroidal estrogenidentifiers iupac name phenyl] dihydrogen phosphate cas number24809-02-7pubchem cid193055chemspider167536unii30l14w008xchemblchembl1162236chemical and physical dataformulac18h24o8p2molar mass430.330 g·mol−13d model (jsmol)interactive image smiles ccc(c1=cc=c(c=c1)op(=o)(o)o)c(cc)c2=cc=c(c=c2)op(=o)(o)o inchi inchi=1s/c18h24o8p2/c1-3-17(13-5-9-15(10-6-13)25-27(19,20)21)18(4-2)14-7-11-16(12-8-14)26-28(22,23)24/h5-12,17-18h,3-4h2,1-2h3,(h2,19,20,21)(h2,22,23,24)/t17-,18+key:jbdiwcwzudnwtl-hdicaceksa-n