The effect of transdermal and vaginal estrogen therapy on markers of postmenopausal estrogen status

Objective: To compare serum 17β-estradiol (E₂), estrone (E₁), estrone sulfate, follicle-stimulating hormone, luteinizing hormone, sex hormone-binding globulin, vaginal pH, and the vaginal maturation indices in women using a low-dose transdermal patch releasing 14 μg of E₂ per day and a vaginal ring releasing 7.5 μg of E₂ per day.

Design: Twenty-four postmenopausal women were randomly assigned to either the patch (n = 12) or the ring (n = 12) for a 12-week study period. Serum E₂, E₁, estrone sulfate, follicle-stimulating hormone, luteinizing hormone, and sex hormone-binding globulin were measured by immunoassay at baseline and 6 and 12 weeks. Vaginal pH was determined at baseline and 6 and 12 weeks. Vaginal cytologic examinations for vaginal maturation index were done at baseline and 12 weeks.

Results: Twenty women completed the study. The patch significantly increased serum E₁ and E₂ levels at 6 and 12 weeks (P < 0.01); there was no significant increase in serum E₁ and E₂ levels with the ring. Both the patch and the ring significantly reduced vaginal pH at 6 (P < 0.001) and 12 (P < 0.001) weeks and significantly reduced the percentage of vaginal parabasal cells at 12 weeks with no significant difference between the two groups. Both preparations increased the proportion of superficial cells; the increase was significant only with the patch (P = 0.04).

Conclusions: A transdermal E₂ skin patch releasing 14 μg of E₂ per day had an effect on vaginal pH and vaginal maturation indices similar to that of a vaginal E₂ ring releasing 7.5 μg of E₂ per day. Therefore, this patch is likely to relieve symptoms of vulvovaginal atrophy.