A comparison of serum oestrogen levels after percutaneous and oral administration of oestradiol-17 beta.

Equivalent doses of oestradiol-17 beta were given orally and percutaneously to eight post-menopausal women and three men. The resultant serum levels of unconjugated immunoreactive oestrogens and total oestrone were followed during 48 hours after hormone administration. A single percutaneous dose of 4 mg oestradiol-17 beta resulted in increased serum levels of oestradiol-17 beta in all individuals. Compared to oral administration the increase in serum oestrogen levels was quite slow and they were maintained for 48 hours. In contrast to the rapid and very marked increase in serum total oestrone following oral administration of oestradiol-17 beta, only a moderate increase was obtained after percutaneous administration and there was a tendency to a biphasic pattern. Topical administration of oestradiol-17 beta might have physiological advantages as the steroid will reach the peripheral circulation without passing the entero-hepatic circulation.