estradiol + estriol

estradiol + estriol, commonly referred to as **Biest**, is a combination of two bioidentical estrogens used primarily in bioidentical hormone replacement therapy (BHRT). Estradiol (E2) is the most potent and abundant endogenous estrogen in premenopausal women, while estriol (E3) is a weaker estrogen metabolite that is produced in high quantities during pregnancy. In the Biest formulation, these two hormones are typically combined in specific ratios—most commonly an 80:20 or 50:50 ratio of estriol to estradiol. The rationale behind this combination is to provide the symptomatic relief associated with estradiol while potentially mitigating its stimulatory effects on the breast and endometrium through the inclusion of the weaker, more selective estriol. Biest is predominantly prepared by compounding pharmacies and is most frequently administered as a transdermal cream or gel to avoid first-pass hepatic metabolism.

Brand names

BiestBiestrogen

Other names

E2 + E3estradiol and estriolBioidentical Hormone Replacement Therapy