Kinetics and pharmacology of estrogens in pre- and postmenopausal women.

With the approach of the menopause and the cessation of ovarian estrogen production, a number of uncomfortable and/or dangerous conditions may be manifested, and are all indications for estrogen replacement therapy. Various routes of estrogen administration are available--oral, subcutaneous implant, intravaginal, and transdermal--each having advantages and disadvantages. There is also a choice possible among replacement hormones, which include the natural estrogens, such as estradiol and estropipate; synthetic estrogens, for example, ethinyl estradiol and diethylstilbestrol; and conjugated equine estrogens. Depending on both route of administration and choice of hormone, there are great differences demonstrable in kinetics and pharmacologic characteristics, which have not been reflected, however, by highly significant differences in clinical outcome so far.