estriol (medication) estriol (medication) estriol (e3), sold under the brand name ovestin among others, is an estrogen medication and naturally occurring steroid hormone which is used in menopausal hormone therapy. it is also used in veterinary medicine as incurin to treat urinary incontinence due to estrogen deficiency in dogs. the medication is taken by mouth in the form of tablets, as a cream that is applied to the skin, as a cream or pessary that is applied in the vagina, and by injection into muscle. this article is about estriol as a medication. for its role as a hormone, see estriol. estriol (medication)clinical datapronunciation/ˈɛstriɒl, -traɪɒl/ ess-tree-ohl trade namesovestin, othersother namesoestriol; e3; 16α-hydroxyestradiol; estra-1,3,5(10)-triene-3,16α,17β-triolroutes ofadministrationby mouth, vaginal, intramuscular injectiondrug classestrogenatc codeg03ca04 (who) g03cc06 (who)legal statuslegal status in general: ℞ (prescription only) pharmacokinetic databioavailabilityoral: ~1–2%vaginal: ~10–20%protein binding92%:• albumin: 91%• shbg: 1%• free: 8%metabolismliver, intestines (conjugation (glucuronidation, sulfation), oxidation, hydroxylation)metabolites• estriol 16α-glucuronide• estriol 3-glucuronide• estriol 3-sulfate• estriol 3-sulfate 16α-gluc.• 16α-hydroxyestrone• others (minor)elimination half-lifeoral: 5–10 hoursim: 1.5–5.3 hours (as e3)iv: 20 minutes (as e3)excretionurine: >95% (as conjugates)identifiers iupac name (8r,9s,13s,14s,16r,17r)-13-methyl-6,7,8,9,11,12,14,15,16,17-decahydrocyclopentaphenanthrene-3,16,17-triol cas number50-27-1 y 1306-04-3514-68-1 (succinate)pubchem cid5756iuphar/bps2821drugbankdb04573 ychemspider5553 yuniifb33469r8ekeggc05141 ychebichebi:27974 ychemblchembl193482 ychemical and physical dataformulac18h24o3molar mass288.387 g·mol−13d model (jsmol)interactive imagemelting point82 to 86 °c (180 to 187 °f) (experimental)solubility in water0.119 mg/ml (20 °c) smiles oc1cc3c(cc1)2cc4((o)(o)c42cc3)c inchi inchi=1s/c18h24o3/c1-18-7-6-13-12-5-3-11(19)8-10(12)2-4-14(13)15(18)9-16(20)17(18)21/h3,5,8,13-17,19-21h,2,4,6-7,9h2,1h3/t13-,14-,15+,16-,17+,18+/m1/s1 ykey:proqiprrnzuxqm-zxxigwhrsa-n y (verify) estriol is well-tolerated and produces relatively few adverse effects. side effects may include breast tenderness, vaginal discomfort and discharge, and endometrial hyperplasia. estriol is a naturally occurring and bioidentical estrogen, or an agonist of the estrogen receptor, the biological target of estrogens like endogenous estradiol. it is an atypical and relatively weak estrogen, with much lower potency than estradiol. when present continuously at adequate concentrations however, estriol produces full estrogenic effects similarly to estradiol. estriol was first discovered in 1930, and was introduced for medical use shortly thereafter. estriol esters such as estriol succinate are also used. although it is less commonly employed than other estrogens like estradiol and conjugated estrogens, estriol is widely available for medical use in europe and elsewhere throughout the world. medical uses estriol is used in menopausal hormone therapy to treat menopausal symptoms, such as hot flashes, vulvovaginal atrophy, and dyspareunia (difficult or painful sexual intercourse). the benefits of estriol on bone mineral density and osteoporosis prevention have been inconsistent and are less clear. estriol has been found to reduce the risk of urinary tract infections and other urogenital symptoms. a combination of estriol and lactobacilli as a dual estrogen and probiotic has been marketed for the treatment of vaginal atrophy and urinary tract infections. estrogen dosages for menopausal hormone therapy route/formestrogenlowstandardhigh oralestradiol0.5–1 mg/day1–2 mg/day2–4 mg/day estradiol valerate0.5–1 mg/day1–2 mg/day2–4 mg/day estradiol acetate0.45–0.9 mg/day0.9–1.8 mg/day1.8–3.6 mg/day conjugated estrogens0.3–0.45 mg/day0.625 mg/day0.9–1.25 mg/day esterified estrogens0.3–0.45 mg/day0.625 mg/day0.9–1.25 mg/day estropipate0.75 mg/day1.5 mg/day3 mg/day estriol1–2 mg/day2–4 mg/day4–8 mg/day ethinylestradiola2.5–10 μg/day5–20 μg/day– nasal sprayestradiol150 μg/day300 μg/day600 μg/day transdermal patchestradiol25 μg/dayb50 μg/dayb100 μg/dayb transdermal gelestradiol0.5 mg/day1–1.5 mg/day2–3 mg/day vaginalestradiol25 μg/day–– estriol30 μg/day0.5 mg 2x/week0.5 mg/day im or sc injectionestradiol valerate––4 mg 1x/4 weeks estradiol cypionate1 mg 1x/3–4 weeks3 mg 1x/3–4 weeks5 mg 1x/3–4 weeks estradiol benzoate0.5 mg 1x/week1 mg 1x/week1.5 mg 1x/week sc implantestradiol25 mg 1x/6 months50 mg 1x/6 months100 mg 1x/6 months footnotes: a = no longer used or recommended, due to health concerns. b = as a single patch applied once or twice per week (worn for 3–4 days or 7 days), depending on the formulation. note: dosages are not necessarily equivalent. sources: see template. available forms (except usa) estriol is available in oral tablet, vaginal cream, and vaginal suppository forms. it is also available over-the-counter or from compounding pharmacies in the form of topical creams. the medication is available both as estriol and in the form of estriol ester prodrugs such as estriol succinate, estriol acetate benzoate, and estriol tripropionate, as well as the polymeric ester prodrug polyestriol phosphate. estriol was originally marketed in the 1930s in the form of oral capsules containing 0.06, 0.12, or 0.24 mg estriol under the brand names theelol (parke-davis) and estriol (lilly, abbott). subsequently, many decades later, oral tablets containing 0.35, 1, or 2 mg estriol were introduced under brand names such as gynäsan, hormomed, ovestin, and ovo-vinces. contraindications