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Premarin, introduced in 1942, is America's most widely prescribed drug, and the third most prescribed in Canada, formerly under the spelling Premarine. It ranks as the number eight drug in the amount of subsidies paid for by Medicaid, based on tax dollars spent on prescriptions. It contains conjugated estrogens as the active ingredient. Other, inactive ingredients are Calcium phosphate tribasic, calcium sulfate, anhydrous (white tablet), calcium sulfate, carnauba wax, cellulose, glyceryl monooleate, lactose, magnesium stearate, methylcellulose, pharmaceutical glaze, polyethylene glycol, stearic acid, sucrose, talc, and titanium dioxide.

Premarin is almost always prescribed as an estrogen substitute for women who have reached menopause, as part of hormone replacement therapy. In fact, it was one of the first drugs available for hormone therapy. It replaces the naturally occuring estrogens that are no longer produced in the same quantities by the body. There is some evidence that taking estrogen can reduce the likelihood of osteoperosis. It is also prescribed commonly for transsexual hormone therapy.

It is marketed world-wide by Wyeth-Ayerst, and distributed by Ayerst Organics Ltd.. Both are subsidaries of American Home Products Co.

Tablets for oral administration are available in 0.3 mg, 0.625 mg, 0.9 mg, 1.25 mg, and 2.5 mg dosages. The tablets are oval and color-coded - green for 0.3 mg, maroon for .625 mg (or white, dye-free tablets), yellow for 1.25 mg, and purple for 2.5 mg.

See conjugated estrogens for more information on sythetic alternatives, side effects, drug interactions, and warnings.

Premarin is obtained from the urine of pregnant mares, hence the name: Premarin (PREgnant MARes' urINe).

The Premarin Controversy:

Premarin is produced on farms created entirely for production of this drug. Horses are impregnated, and kept in small stalls so their urine can be harvested for processing, in bags that are worn at all times. The bags often chafe and leak, causing sores and infections. The stalls are often small enough that the mares can barely move around. They are often given only minimal water, to keep the urine more concentrated. In other words, this is probably the most cruelly-derived drug a vegan will ever encounter.

Once the horses give birth, the foals are usually transported to one of three slaughterhouses in Canada. The meat from the foals is shipped to various countries that consume the meat, such as France and Japan. The mare is then impregnated again as soon as possible. And once the estrogen levels in the urine drop enough, the mares themselves are sent to the slaughterhouse.

Most of the farms are located in Canada, in Manitoba, Alberta, and Saskatchewan. A few farms are located in North Dakota, in the USA. Production produces revenues close to $2 billion dollars annually, and is Canada's most lucrative pharmaceutical export.

There are synthetic alternatives, produced entirely in the lab. Industry spokespeople say the lab-produced substance costs twice as much to produce, and none of them are currently approved as generic equivalents, because of the delta 8,9 DHES factor that they lack. Under the Waxman-Hatch Act of 1984, as a generic substitute, it must meet an "identical active ingredients/efficacy" test.

Currently, the demand is rising so quickly, especially due to the Baby Boomer crowd reaching menopause age, that the Canadian subsidiary Ayerst Organics, Inc. is building a new factory. This factory, according to the company's annual report, will triple the output, to nine million gallons of urine per annum.

Many animal rights groups are now actively fighting to inform women of the source of Premarin and the treatment of animals from which the drug is derived. They are encouraging the use of synthetic replacements, and in some cases, questioning the value of hormone replacement therapy in general.

RxLine - http://www.rxline.com/
Premarin.org - http://www.premarin.org/
About.com - http://www.about.com/

Brand name of conjugated estrogens


  • Tablets: Estrogen deficiency. Moderate to severe menopause vasomotor symptoms. Postmenopausal osteoporosis. Atrophic vaginitis.
  • Injection: Abnormal uterine bleeding due to a hormone imbalance.
  • Vaginal cream: vaginal or vulvar atrophy.

Dosage for adults

  • Tablets: May be given cyclically (3 weeks on, 1 week off) or continuously. For estrogen deficiency or hot flashes and other vasomotor symptoms start with 0.625 mg/day. For vaginal dryness associated with menopause give 0.3 to 1.25 mg or more daily. For prevention of osteoporosis give 0.625 mg/day along with increased calcium in the diet of 1 to 1.5 grams/day and Vitamin D.
  • Injection: Non-pregnant women: 25 mg IV or IM. Repeat in six to twelve hours if necessary.
  • Vaginal cream: 0.5 to 2 grams daily in a cyclical pattern (3 weeks on, 1 week off).

Dosage for children
Not applicable.

How supplied

  • Tablets of 0.3mg, 0.625mg, 1.25mg, and 2.5mg.
  • Injection - 25mg/cc vials.
  • Vaginal cream - 42.5g tube with applicator; 0.625 mg/gram

Additional Information

Premarin was the #3 prescribed medication in the US in 2001. The name "Premarin" is said to have been derived from the source of the conjugated estrogens - PREgnant MAre uRINe. Please see the excellent writeup by Saige for more information about this medication and some of the controversy surrounding it.

Date of most recent Update: August 5, 2002

Further information is available in the writeup for the generic name(s) of this medication.

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