Ethinylestradiol

Ethinylestradiol is a synthetic estrogen used in contraceptives and other hormone treatments. Its 17α-ethinyl group makes it orally active by slowing its breakdown in the liver.

Estrogen receptor: A nuclear receptor activated by estrogens that regulates gene expression and other cellular processes. Ethinylestradiol produces many of its effects by activating estrogen receptors.
Combined oral contraceptive pill: An oral contraceptive combining an estrogen with a progestin to prevent pregnancy. Ethinylestradiol is the estrogen in many combined pills, paired with different progestins.
Estradiol: The principal estrogen produced by the ovaries during the reproductive years. Unlike ethinylestradiol, estradiol is a natural human estrogen and undergoes extensive first-pass metabolism.
Venous thromboembolism: Blood clot formation in a vein, including deep-vein thrombosis and pulmonary embolism. Ethinylestradiol-containing contraceptives increase clot risk compared with nonuse.
Inauguration of oral contraception: The introduction of the first widely approved oral contraceptive in the early 1960s. Early combined pills used ethinylestradiol, establishing it as a major contraceptive estrogen.
Hypothalamic–pituitary–gonadal axis: The hormonal signaling system linking the hypothalamus, pituitary gland, and reproductive organs. Ethinylestradiol suppresses this axis, helping prevent the hormonal surge that triggers ovulation.
Vaginal ring: A flexible device placed in the vagina that releases hormones for contraception. Some rings deliver ethinylestradiol together with a progestin through vaginal absorption.
Estradiol valerate: An ester prodrug converted in the body to estradiol. It provides an alternative estrogen in some contraceptive and hormone-treatment formulations.
Stroke: Brain injury caused by interrupted blood flow or bleeding in the brain. Estrogen-containing contraception can raise ischemic stroke risk, especially with certain risk factors.
Frank B. Colton: An American chemist who synthesized ethinylestradiol in 1938. Colton’s synthesis produced the compound later adopted in oral contraceptives.

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