Development of a vaginal ring for achieving physiologic levels of 17β-estradi0l in hypoestrogenic women¹

The ability of polysiloxane vaginal rings containing 17β -Estradiol (E₂) to deliver E₂ into the systemic circulation at a steady rate over long periods of time was evaluated in castrate and postmenopausal volunteers. Standard laminar designs, used to release contraceptive gestagens, deliver low levels of E₂ (about 50 pg/ml) and only for 1 month. With a modified design, E₂ levels of 109 to 159 pg/ml were maintained for at least 3 months, and circulating gonadotropins were infpressed to values approaching the premenopausal range. This homogeneous design provides for physiologic replacement of E₂ as well as a practical research tool for studying chronic effects of E₂ in human subjects.