Systemic absorption and sustained effects of vaginal estrogen creams.

Systemic absorption and sustained effects of two estrogen vaginal cream preparations (Premarin and Estrace) were measured in 29 postmenopausal women receiving daily applications. With both preparations, vaginal absorption of estrogens into the systemic circulation was rapid, efficient, and sustained. It is apparent that estrogen vaginal cream preparations, as widely used in clinical practice for their local effects on the vaginal mucosa, actually result in sustained high estrogen levels in the systemic circulation. The vaginal route shows promise when systemic estrogen therapy is indicated, but is dangerous when estrogen is contraindicated.