Drug Groups

approved

Description

A semisynthetic alkylated estradiol with a 17-alpha-ethinyl substitution. It has high estrogenic potency when administered orally, and is often used as the estrogenic component in oral contraceptives. [PubChem]

Indication

For treatment of moderate to severe vasomotor symptoms associated with the menopause, female hypogonadism, prostatic carcinoma-palliative therapy of advanced disease, breast cancer, as an oral contraceptive, and as emergency contraceptive.

Pharmacology

Ethinyl estradiol is a synthetic derivative of the natural estrogen estradiol. It is one of two estrogens currently used in oral contraceptive pills. The other, mestranol, is converted to ethinyl estradiol before it is biologically active. Ethinyl estradiol and norethindrone are used together as an oral contraceptive agent.

Toxicity

Oral, mouse LD₅₀: 1737 mg/kg. Symptoms of overdose include nausea and vomiting, and withdrawal bleeding may occur in females.

Affected Organisms

Biotransformation

Hepatic. Quantitatively, the major metabolic pathway for ethinyl estradiol, both in rats and in humans, is aromatic hydroxylation, as it is for the natural estrogens.

Absorption

Rapid and complete absorption follows oral intake of ethinyl estradiol (bioavailability 43%).

Half Life

36 +/- 13 hours

Protein Binding

97%

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