Ethinylestradiol

Ethinylestradiol
Clinical data


Pronunciation	/ˌɛθᵻnᵻlˌiːstrəˈdaɪ.əl/
Trade names	Estinyl, others
AHFS/Drugs.com	International Drug Names
MedlinePlus	a604032
Pregnancy category	X (USA)
Routes of administration	• By mouth (tablet) • Transdermal (patch) • Vaginal (ring)
ATC code	G03CA01 (WHO) L02AA03 (WHO)
Legal status
Legal status	℞ (Prescription only)
Pharmacokinetic data
Bioavailability	38–48%
Protein binding	97–98% (to albumin; does not bind to SHBG)
Metabolism	Liver (primarily CYP3A4)
Biological half-life	7–36 hours
Excretion	Feces: 62% Urine: 38%
Identifiers
IUPAC name (8R,9S,13S,14S,17R)-17-ethynyl-13-methyl-7,8,9,11,12,14,15,16-octahydro-6H-cyclopenta[a]phenanthrene-3,17-diol
Synonyms	17α-Ethynylestradiol; 17α-Ethynylestra-1,3,5(10)-triene-3,17β-diol; NSC-10973
CAS Number	57-63-6^Y
PubChem (CID)	5991
IUPHAR/BPS	7071
DrugBank	DB00977^Y
ChemSpider	5770^Y
UNII	423D2T571U^Y
KEGG	D00554^Y
ChEBI	CHEBI:4903^Y
ChEMBL	CHEMBL691^N
ECHA InfoCard	100.000.311
Chemical and physical data
Formula	C₂₀H₂₄O₂
Molar mass	296.403 g/mol
3D model (Jmol)	Interactive image
SMILES Oc1cc4c(cc1)[C@H]3CC[C@]2([C@@H](CC[C@]2(C#C)O)[C@@H]3CC4)C
InChI InChI=1S/C20H24O2/c1-3-20(22)11-9-18-17-6-4-13-12-14(21)5-7-15(13)16(17)8-10-19(18,20)2/h1,5,7,12,16-18,21-22H,4,6,8-11H2,2H3/t16-,17-,18+,19+,20+/m1/s1^Y Key:BFPYWIDHMRZLRN-SLHNCBLASA-N^Y
^NY (what is this?)

Ethinylestradiol (EE) is a synthetic, steroidal estrogen and a derivative of estradiol, the major endogenous estrogen in humans. It is an estrogen that is active when taken by mouth and is used in almost all formulations of combined birth control pills, and is nearly the exclusive estrogen used for this purpose.

EE was patented in 1935 and came into medical use in 1943. It started being used in COCs in 1964.

As Estinyl, EE was formerly used for hormone replacement therapy in menopause and the treatment of female hypogonadism, loss of menstruation, dysmenorrhea, acne, prostate cancer, and breast cancer. However, in more recent times, EE is mainly used in COCs. In contraception, due to concerns of unopposed estrogen action and the possible increased risk of endometrial cancer that accompanies this, EE is formulated in combination with progestins. EE is little used in menopausal hormone replacement therapy.

EE has been used at very high dosages (1–2 mg/day) in the treatment of prostate cancer.

EE should be avoided in women with a history of or known susceptibility to thrombosis (blood clots), particularly venous thromboembolism (VTE).

Due to risk of cholestatic hepatotoxicity, it is widely considered that COCs containing EE should be avoided in women with a history of cholestasis of pregnancy, hepatic tumors, active hepatitis, and familial defects in biliary excretion.