Oestriol

Estriol is a weak endogenous estrogen formed by irreversible transformation of estradiol and estrone

• oestriol (estriol E3)
  • oestrogen the placenta secretes during pregnancy
  • alos is the peripheral metabolite of oestradiol and o estrone
  • is not secreted by the ovary
• has a lower estrogenic potency than estradiol does (ranging from 1/10 to 1/100, 1/80 most often cited)
• and a greater relative affinity for alpha than for beta estrogenic receptors (È3:1)
• estriol is a very well-known molecule with a long-lasting clinical experience
• estriol has been demonstrated to be safe in terms of endometrial proliferation (2)

Reference:

• Hamilton KJ et al. Estrogen Hormone Biology.Curr Top Dev Biol. 2017; 125: 109–146.
• Cano A et al. The therapeutic effect of a new ultra low concentration estriol gel formulation (0.005% estriol vaginal gel) on symptoms and signs of postmenopausal vaginal atrophy: results from a pivotal phase III study.Menopause 2012 Oct;19(10):1130-9