Serum levels of oestrogens, progesterone, follicle-stimulating hormone and sex-hormone-binding globulin during simultaneous vaginal administration of 17β-oestradiol and progesterone in the pre- and post-menopause

Serum concentrations of 17β-oestradiol (E₂), unconjugated oestrone (E₁), total oestrone (tE₁), progesterone (P), follicle-stimulating hormone (FSH) and sex-hormone-binding globulin (SHBG) were measured before and after daily intravaginal administration of 250 μg micronized E₂ and 10 mg micronized P for 14 days to 12 post-menopausal and for 1 day only (during cycle days 5–8) to 11 pre-menopausal women. In the post-menopausal women the levels of all steroids increased to maximum values on day 1, 8–10 h after administration and fell thereafter. In the pre-menopausal women the steroid concentrations rose slowly to a plateau level 10–15 h after administration. Significantly higher absorption of E₂ and E₁ (area under the curve increments) was noted in the post-menopausal than in the pre-menopausal women.

In the post-menopausal women the steroid levels measured on days 7 and 14 corresponded to those observed in the very early or late luteal phase. Area under the curve increments were usually smaller on days 7 and 14 than on day 1 and the absorption kinetics altered to a ‘pre-menopausal’ pattern. FSH levels were significantly reduced as from 12 h after administration on day 1 and onwards. A slight (10%) but significant increase in SHBG levels was noted on day 14. It was concluded that the combined E₂ and P treatment used in this investigation brings about a physiological response with only minimal side effects on the liver as judged from changes in SHBG concentrations.