nomegestrol nomegestrol nomegestrol (inn), also known as 19-normegestrol, is a steroidal progestin which was patented in 1975 but was never marketed. it is the parent compound of nomegestrol acetate, which is marketed as a progestin. this article is about a non-clinically used progestin compound. for the pharmaceutical drug, see nomegestrol acetate. nomegestrolclinical dataother names19-normegestrol; 6-methyl-17α-hydroxy-δ6-19-norprogesterone; 17α-hydroxy-6-methyl-19-norpregna-4,6-diene-3,20-dioneatc codeg03db04 (who) identifiers iupac name (17α)-17-acetyl-17-hydroxy-6-methylestra-4,6-dien-3-one cas number58691-88-6pubchem cid68783chemspider62024unii10f89177cokeggd07222chemical and physical dataformulac21h28o3molar mass328.452 g·mol−13d model (jsmol)interactive image smiles o=c4\c=c3\c(=c/1(cc2((o)(c(=o)c)cc12)c)3cc4)c inchi inchi=1s/c21h28o3/c1-12-10-18-16(15-5-4-14(23)11-17(12)15)6-8-20(3)19(18)7-9-21(20,24)13(2)22/h10-11,15-16,18-19,24h,4-9h2,1-3h3/t15-,16-,18-,19+,20+,21+/m1/s1key:kzuiyqjtuiacig-ybzcjvabsa-n nomegestrol shows relatively low affinity for the progesterone receptor, only about 4% of that of progesterone and about 1.6% of that of nomegestrol acetate in one assay.