Estriol

A hydroxylated metabolite of estradiol or estrone that has a hydroxyl group at C3-beta, 16-alpha, and 17-beta position. Estriol is a major urinary estrogen. During pregnancy, large amount of estriol is produced by the placenta. Isomers with inversion of the hydroxyl group or groups are called epiestriol. Though estriol is used as part of the mainly North American phenomenon of bioidentical hormone replacement therapy, it is not approved for use by the FDA or Health Canada. It is however available in the United States by prescription filled only by compounding pharmacies. It has also been approved and marketed throughout Europe and Asia for approximately 40 years for the treatment of post-menopausal hot flashes. It is grouped under the following drug class(es): Estrogens and Steroids. The directory classifies it as a commercial API with a semi-synthetic source/manufacturing origin. Other names for this substance include Oestriol, Trihydroxyestrin and Aacifemine. Its PubChem CID is 5756.