Biological and endocrine aspects of transdermal 17 beta-oestradiol administration in post-menopausal women

The plasma protein distribution of oestradiol (E2) and oestrone (E1) during transdermal E2 administration (100 micrograms/24 hr) was studied in 12 post-menopausal women. The E2 and E1 levels observed were 43-83 pg/ml and 37-73 pg/ml, respectively. The levels of the free, albumin-bound and sex-hormone-binding globulin (SHBG) bound fractions were in the ranges 1.4-1.9%, 60-65% and 35-45%, respectively, in the case of E2, and 2.8-3.0%, 80-89% and 15-20%, respectively, in that of E1. The SHBG levels also remained unaltered. It was concluded that transdermal administration of E2 at the dosage employed produces a physiological plasma protein distribution of E2 and E1 and does not affect liver protein production.