Estradiol-delivering vaginal rings for hormone replacement therapy

Objectives: This study was undertaken to determine the relief of climacteric symptoms by vaginal rings delivering estradiol and to monitor estrogen levels. Study Design: Rings releasing in vitro either 60 or 140 μg/d estradiol were used by 35 women who had undergone hysterectomy for each dose level. Hot flash and night sweat incidences, vaginal conditions, and complaints were recorded at clinic visits pretreatment and at 1 week, 2 weeks, 1 month, and monthly thereafter through 6 months. Serum samples were assayed for estradiol, estrone, and estrone sulfate. Results: Hot flash incidence was reduced by about 80% with either ring. Vaginal conditions and mood were improved. Fourteen of 70 women discontinued ring use during the trial, 5 because of ring expulsions. Mean (±SD) estradiol levels were 123 ± 48 and 307 ± 93 pmol/L for the low and high dosage levels, respectively. Mean estrone levels exceeded estradiol levels by 1.7-fold for the higher dosage ring and 2.6-fold for the lower dosage ring. Increases in estrone sulfate concentrations were many times greater than those of estradiol or estrone. Conclusions: Vaginal rings are an acceptable method of delivery for periods of ≥6 months of doses of estradiol that reduce vasomotor symptoms and improve vaginal conditions. There was little difference in these responses between the 2 dosage levels. (Am J Obstet Gynecol 1999;181:1400-6.)