estradiol monopropionate estradiol monopropionate estradiol propionate (ep), also known as estradiol monopropionate or estradiol 17β-propionate and sold under the brand names acrofollin, akrofollin, and follhormon, is an estrogen medication and estrogen ester which is no longer marketed. it is the c17β propionate ester of estradiol. ep was provided in an oil solution and was administered by intramuscular injection. the medication was first marketed by 1938 or 1939. affinities and estrogenic potencies of estrogen esters and ethers at the estrogen receptors estrogen other names rba (%)a rep (%)b er erα erβ estradiol e2 100 100 100 estradiol 3-sulfate e2s; e2-3s ? 0.02 0.04 estradiol 3-glucuronide e2-3g ? 0.02 0.09 estradiol 17β-glucuronide e2-17g ? 0.002 0.0002 estradiol benzoate eb; estradiol 3-benzoate 10 1.1 0.52 estradiol 17β-acetate e2-17a 31–45 24 ? estradiol diacetate eda; estradiol 3,17β-diacetate ? 0.79 ? estradiol propionate ep; estradiol 17β-propionate 19–26 2.6 ? estradiol valerate ev; estradiol 17β-valerate 2–11 0.04–21 ? estradiol cypionate ec; estradiol 17β-cypionate ?c 4.0 ? estradiol palmitate estradiol 17β-palmitate 0 ? ? estradiol stearate estradiol 17β-stearate 0 ? ? estrone e1; 17-ketoestradiol 11 5.3–38 14 estrone sulfate e1s; estrone 3-sulfate 2 0.004 0.002 estrone glucuronide e1g; estrone 3-glucuronide ? <0.001 0.0006 ethinylestradiol ee; 17α-ethynylestradiol 100 17–150 129 mestranol ee 3-methyl ether 1 1.3–8.2 0.16 quinestrol ee 3-cyclopentyl ether ? 0.37 ? footnotes: a = relative binding affinities (rbas) were determined via in-vitro displacement of labeled estradiol from estrogen receptors (ers) generally of rodent uterine cytosol. estrogen esters are variably hydrolyzed into estrogens in these systems (shorter ester chain length -> greater rate of hydrolysis) and the er rbas of the esters decrease strongly when hydrolysis is prevented. b = relative estrogenic potencies (reps) were calculated from half-maximal effective concentrations (ec50) that were determined via in-vitro β‐galactosidase (β-gal) and green fluorescent protein (gfp) production assays in yeast expressing human erα and human erβ. both mammalian cells and yeast have the capacity to hydrolyze estrogen esters. c = the affinities of estradiol cypionate for the ers are similar to those of estradiol valerate and estradiol benzoate (figure). sources: see template page. not to be confused with estradiol 3-propionate or estradiol dipropionate. estradiol monopropionateclinical datatrade namesacrofollin, akrofollin, follhormonother namesep; estradiol monopropionate; estradiol propanoate; estradiol 17β-propionate; estradiol 17β-propanoate; estra-1,3,5(10)-trien-3,17β-diol 17β-propionateroutes ofadministrationintramuscular injectiondrug classestrogen; estrogen esteridentifiers iupac name phenanthren-17-yl] propanoate cas number3758-34-7pubchem cid19571chemspider18438uniik31pc34297comptox dashboard (epa)dtxsid4048985 echa infocard100.021.059 chemical and physical dataformulac21h28o3molar mass328.452 g·mol−13d model (jsmol)interactive image smiles ccc(=o)oc1ccc2c1(ccc3c2ccc4=c3c=cc(=c4)o)c inchi inchi=1s/c21h28o3/c1-3-20(23)24-19-9-8-18-17-6-4-13-12-14(22)5-7-15(13)16(17)10-11-21(18,19)2/h5,7,12,16-19,22h,3-4,6,8-11h2,1-2h3/t16-,17-,18+,19+,21+/m1/s1key:pqcrzwcsvwbysc-agrfsfnasa-n