Low-dose 17 beta-oestradiol during maintenance therapy--a pharmacokinetic and pharmacodynamic study.

The vaginal absorption of oestradiol was studied during maintenance therapy with low-dose oestradiol. Six women with severe vaginal atrophy due to oestrogen deficiency were treated with a vaginal tablet containing 25 micrograms 17 beta-oestradiol. Initially, a daily dose was given for 2 weeks, followed by maintenance therapy with twice weekly treatment for another 10 weeks. The plasma concentrations of unconjugated oestrone and oestradiol were measured before oestrogen treatment was started at the beginning of the study. After 3 months of treatment frequent plasma sampling over a period of 24 h was performed. Gonadotrophins, vaginal and urethral cytology, clinical findings and subjective symptoms were assessed at the beginning and end of the study. Plasma concentrations of unconjugated oestradiol were at all times within the limits of postmenopausal values, but showed a slight but not statistically significant elevation after 3 months compared to pretreatment values. Plasma concentrations of unconjugated oestrone were in the low postmenopausal range throughout the study. LH levels were unaffected during the study, while FSH was somewhat lowered, but still well within the postmenopausal range. Vaginal and urethral cytology showed maturation with almost complete disappearance of parabasal cells. Clinical and subjective improvement was statistically significant during the treatment period.