Doses of estradiol of as high as 200 mg per day by intramuscular injection for several weeks have been administered to humans in studies. Serious adverse effects have not been described following acute overdose of large doses of estrogen- and progestogen-containing birth control pills by small children. Symptoms of estrogen overdosage may include nausea, vomiting, bloating, increased weight, water retention, breast tenderness, vaginal discharge, vaginal bleeding, heavy legs, and leg cramps. These side effects can be diminished by reducing the estrogen dosage. Interactions
Inducers of cytochrome P450 enzymes like CYP3A4 such as St. Johns wort, phenobarbital, carbamazepine and rifampicin decrease the circulating levels of estradiol by accelerating its metabolism, whereas inhibitors of cytochrome P450 enzymes like CYP3A4 such as erythromycin, cimetidine, clarithromycin, ketoconazole, itraconazole, ritonavir and grapefruit juice may slow its metabolism resulting in increased levels of estradiol in the circulation. There is an interaction between estradiol and alcohol such that alcohol considerably increases circulating levels of estradiol during oral estradiol therapy and also increases estradiol levels in normal premenopausal women and with parenteral estradiol therapy. This appears to be due to a decrease in hepatic 17β-hydroxysteroid dehydrogenase type 2 (17β-HSD2) activity and hence estradiol inactivation into estrone due to an alcohol-mediated increase in the ratio of NADH to NAD in the liver. Spironolactone may reduce the bioavailability of high doses of oral estradiol. Pharmacology
Pharmacodynamics
Estradiol is an estrogen, or an agonist of the estrogen receptors (ERs), the ERα and ERβ. It is also an agonist of membrane estrogen receptors (mERs), including the GPER, Gq-mER, ER-X, and ERx.
Examples of major brand names in which estradiol has been marketed in include Climara, Climen, Dermestril, Divigel, Estrace, Natifa, Estraderm, Estraderm TTS, Estradot, Estreva, Estrimax, Estring, Estrofem, EstroGel, Evorel, Fem7 (or FemSeven), Imvexxy, Menorest, Oesclim, OestroGel, Sandrena, Systen, and Vagifem. Estradiol valerate is marketed mainly as Progynova and Progynon-Depot, while it is marketed as Delestrogen in the U.S. Estradiol cypionate is used mainly in the U.S. and is marketed under the brand name Depo-Estradiol. Estradiol acetate is available as Femtrace, Femring, and Menoring.Estradiol is also widely available in combination with progestogens. It is available in combination with norethisterone acetate under the major brand names Activelle, Cliane, Estalis, Eviana, Evorel Conti, Evorel Sequi, Kliogest, Novofem, Sequidot, and Trisequens; with drospirenone as Angeliq; with dydrogesterone as Femoston, Femoston Conti; and with nomegestrol acetate as Zoely. Estradiol valerate is available with cyproterone acetate as Climen; with dienogest as Climodien and Qlaira; with norgestrel as Cyclo-Progynova and Progyluton; with levonorgestrel as Klimonorm; with medroxyprogesterone acetate as Divina and Indivina; and with norethisterone enantate as Mesigyna and Mesygest. Estradiol cypionate is available with medroxyprogesterone acetate as Cyclo-Provera, Cyclofem, Feminena, Lunelle, and Novafem; estradiol enantate with algestone acetophenide as Deladroxate and Topasel; and estradiol benzoate is marketed with progesterone as Mestrolar and Nomestrol.Estradiol valerate is also widely available in combination with prasterone enantate (DHEA enantate) under the brand name Gynodian Depot. Availability
Estradiol and/or its esters are widely available in countries throughout the world in a variety of formulations.