Ethinylestradiol
From Wikipedia, the free encyclopedia
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Ethinylestradiol
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| Systematic (IUPAC) name | |
| 17-ethynyl-13-methyl- 7,8,9,11,12,13,14,15,16,17- decahydro-6H-cyclopenta[a] phenanthrene-
3,17-diol |
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| Identifiers | |
| CAS number | |
| ATC code | G03 L02AA03 |
| PubChem | |
| DrugBank | |
| Chemical data | |
| Formula | C20H24O2 |
| Mol. mass | 296.403 |
| Pharmacokinetic data | |
| Bioavailability | 97% is bound |
| Metabolism | Liver |
| Half life | 36±13 hours |
| Excretion | Urine |
| Therapeutic considerations | |
| Pregnancy cat. |
X (USA) |
| Legal status |
Rx-only (U.S.) |
| Routes | Oral, transdermal |
Ethinylestradiol, also ethinyl estradiol (EE), is a synthetic derivative of estradiol. Ethinyl estradiol is orally bio-active and the estrogen in almost all modern formulations of combined oral contraceptive pills (the Pill). It is one of the most commonly used medications.
While estradiol is readily absorbed when taken orally, it is also quickly inactivated by the liver. Substitution at C17 of the estrane steroid with an ethinyl group proved to provide an estrogen that is much more resistant to degradation and paved the way for the development of oral contraceptives.
EE is absorbed in the small intestine and reaches a serum peak about 2 hours later. It undergoes extensive metabolism in the liver involving the cytochrome P450 3A4 isoenzyme. EE and its metabolites are in excreted with the bile. Due to the effect of enterohepatic circulation as second peak is seen several hours later. Individually, wide variations exist in the overall absorption process, and can be further modified by drug (i.e. antibiotics) that affect the enterohepatic circulation or liver enzymes. In circulation EE is almost fully bound to plasma albumin. It is metabolized by hydroxylation of the aromatic ring and excreted in both, feces and urine, in part as glucuronide and sulfate conjugate.
EE is hormonally effective by activating the estrogen receptor and thus used as an estrogen. It finds its most common use in the estrogen-progestin combination preparations of oral contraceptives. Over time, formulations have decreased the EE dose from as high as 100 μg to as low as 20 μg.
All the contraindication and precautions apply for EE as with other estrogen medications.
Estinyl is a preparation of EE alone that is used for the management of menopausal symptoms and female hypogonadism.
EE is released into the environment as a xenoestrogen.
[edit] See also
[edit] References
- RxList.com - Estinyl (ethinyl estradiol)
