Endometrial effects of transdermal estradiol/norethisterone acetate.

The efficacy of transdermal norethisterone acetate in sequence with transdermal estradiol has been investigated in a multicenter study of 136 post-menopausal women to determine the incidence of endometrial hyperplasia, the effects on the vaginal cytology and the control of bleeding. Treatment consisted of 12 cycles of 4 weeks each (2 weeks estradiol 50 micrograms/day followed by 2 weeks of a new combined patch delivering norethisterone acetate 0.25 mg/day and estradiol 50 micrograms/day). Endometrial histology was assessed by two pathologists. Of the 136 pre-treatment biopsies 89% provided no material, an inadequate sample or an inactive (atrophic or non-secretory) endometrium. Of the post-treatment biopsies from 110 women who completed the study: 65% showed secretory, 3% proliferative and 24% inadequate material or inactive endometrium. Hyperplasia was found in two biopsies (2%); in one of these focal atypical hyperplasia was agreed by both pathologists, in another a hyperplastic endometrial polyp was diagnosed by one pathologist. The bleeding was regular in 80% of the 1195 cycles and irregular in 11%. No bleeding occurred in 9% of the cycles. Vaginal cytology showed a significant shift towards increased maturation during treatment.