Natural estrogens, predominantly estradiol, stimulate normal development of primary and secondary sex characteristics in women. Furthermore, they play an important role in the ovarian cycle and concomitant uterine and vaginal changes. Estrogens exert their action via binding to a cytoplasmic estrogen receptor. The estrogen receptor complex binds to estrogen-responsive elements on the DNA, resulting in transcription of specific genes and subsequent proteins. Effects of estrogens are diverse and affect many kinds of body cells (e.g. skin, calcium metabolism, and nervous system).
Estradiol and estrone are natural estrogens; ethinylestradiol belongs to the group of synthetic estrogens, mainly used in the combined oral contraceptives. Estradiol is used to treat hypogonadism and premature ovarian failure. Other therapeutic applications are: menopausal complaints, osteoporosis and hormonal therapy for certain tumors. Different kinds of administration exist for estrogens, depending on the indication: oral, vaginal, intramuscular, nasal, subcutaneous, and transdermal. The dosage depends on the disease that is treated. For contraception doses between 30 and 50 μg are normal.
I. Hyperplasia of endometrium and carcinoma of the mammary gland are associated with estrogens use.
II. Estrogens stimulate osteoporosis.
Extra info: The duration of the therapy and the dosage are important factors in the risk on malignancies. Estrogens inhibit osteoporosis.