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Systematic (IUPAC) name
sodium 13-methyl-17-oxo-3-sulfonatooxy-7,8,9,11,12,14,15,16-octahydro-6H-cyclopenta[ a] phenanthrene
CAS number 12126-59-9
ATC code G03CA57
PubChem 9919
DrugBank APRD00396
Chemical data
Formula C18H21NaO5S 
Mol. mass 372.412 g/mol
SMILES search in eMolecules, PubChem
Synonyms conjugated estrogens
equilin sulfate
Pharmacokinetic data
Bioavailability  ?
Protein binding >90%
Metabolism  ?
Half life 7.2 hours
Excretion renal
Therapeutic considerations
Pregnancy cat.


Legal status

Prescription only

Routes Oral, topical

Premarin is the commercial name for compound drug consisting primarily of conjugated estrogens. Isolated from mare's urine (PREgnant MARes' urINe), it is manufactured by Wyeth Pharmaceuticals and has been marketed since 1942. It is available in oral (0.3/ 0.45/ 0.625/ 1.25mg), IV, and topical form.



The major forms of estrogen in Premarin are estrone (>50%), equilin (15-25%) and equilenin. The estrogens in Premarin are often called "conjugated equine estrogens" (CEE) because the estrogen molecules are generally present with hydrophilic side-groups attached such as sulfate. Thus, estrone sulfate is actually the major molecule in Premarin. Estrone sulfate is easily absorbed into the blood after Premarin pills are taken by women. Estrone sulfate is converted to estradiol, an active estrogen normally found in women. It is not clear if estrogens such as equilin that are foreign to the human body have effects in women that are significantly different from the estrogens like estradiol that are normally made in the human body.


Premarin is indicated for the treatment of mild to severe vasomotor symptoms of the menopause, prevention of osteoporosis, and treatment of vaginal and vulvar atrophy. Premarin has been one of the most widely used drugs in the United States. Premarin became the form of estrogen most commonly used for hormone replacement therapy.


Premarin is the subject of some contention. Animal rights activists claim that animal husbandry and urine collection methods used in Premarin's production cause undue stress and suffering to the mares involved.[1] Additionally, it is proposed that there is an overabundance of poorly bred foals produced by Pregnant Mare Urine (PMU) farms each year. However, PMU horses only represent 0.01% of equines in North America [2]. There has been an increase in the number of registered horses on PMU ranches with almost all horses now being registered stock. [3] The vast majority of these purebred foals are sold for pleasure riding and driving. [4]


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See also


This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Premarin". A list of authors is available in Wikipedia.
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