melengestrol acetate melengestrol acetate melengestrol acetate (mlga), sold under the brand names heifermax and mga among others, is a progestin medication which is used in animal reproduction. it is not approved for use in humans, and is instead used as an implantable contraceptive for captive animals in zoos and other refuges, and is also used as a feed additive to promote growth in cattle, a purpose it is licensed for in the united states and canada. not to be confused with megestrol acetate. melengestrol acetateclinical datatrade namesheifermax, mgaother namesmga; mla; mlga; melengesterol acetate; methylsuperlutin; u-21240; bdh-1921; 17α-acetoxy-16-methylene-6-methyl-6-dehydroprogesterone; 17α-acetoxy-16-methylene-6-methylpregna-4,6-diene-3,20-dionedrug classprogestogen; progestin; progestogen esteratc codenoneidentifiers iupac name phenanthren-17-yl] acetate cas number2919-66-6pubchem cid250948drugbankdb14659chemspider219803unii4w5hds3936keggd04900comptox dashboard (epa)dtxsid5048184 echa infocard100.018.964 chemical and physical dataformulac25h32o4molar mass396.527 g·mol−13d model (jsmol)interactive image smiles o=c4\c=c3\c(=c/1(cc2((oc(=o)c)(c(=c)\c12)c(=o)c)c)3(c)cc4)c inchi inchi=1s/c25h32o4/c1-14-11-19-20(23(5)9-7-18(28)13-21(14)23)8-10-24(6)22(19)12-15(2)25(24,16(3)26)29-17(4)27/h11,13,19-20,22h,2,7-10,12h2,1,3-6h3/t19-,20+,22+,23-,24+,25+/m1/s1key:udkabvsqkjnzbh-dwnqpyozsa-n uses animal reproduction mlga is used in animal reproduction. pharmacology pharmacodynamics mlga is a progestogen, and hence is an agonist of the progesterone receptor. it has been found to possess 73% of the affinity of progesterone for the progesterone receptor in rhesus monkey uterus. chemistry