Estrogen (Conjugated Estrogens CSD) | The Canadian Encyclopedia


Estrogen (Conjugated Estrogens CSD)

Conjugated Estrogens CSD (Canadian Standard Drug) is a female sex hormone complex produced primarily in the ovaries. Many of the female body's vital metabolic and physiologic processes are controlled by estrogen.

Estrogen (Conjugated Estrogens CSD)

Conjugated Estrogens CSD (Canadian Standard Drug) is a female sex hormone complex produced primarily in the ovaries. Many of the female body's vital metabolic and physiologic processes are controlled by estrogen. The estrogenic complex has specific effects on the female sex organs and sex characteristics. It also acts, however, as a building block and metabolic regulator on other tissues and systems such as the skin and skeletal musculature in women. Pharmaceutical estrogen products are divided into those used for conception control and those used for their metabolic and physiologic effects alone. Imbalances in estrogen levels can cause a variety of problems. Fluid retention, weight gain and migraines can be associated with high estrogen levels, while low estrogen can cause bone loss, hot flashes, urinary problems and changes in memory. Women may opt to use hormone replacement therapy (HRT) to cope with such imbalances, particularly during perimenopause.

The Discovery of Estrogen

In 1885 the French physiologist Claude Bernard discovered that, in addition to external excretions, many of the body's glands produce internal secretions which may affect all or specific body organs. In 1906 investigators discovered that the ovaries secrete a hormone that produces the phenomenon of estrus (or heat), hence, estrogen. Other researchers made further explorations into the action of estrogen. At McGill, J.B. COLLIP, D.L. Thomson and J.S.L. Browne studied placental and ovarian hormones and, in 1930, published 3 papers in the Canadian Medical Association Journal describing isolation of the estrogen complex in pure form from a human placenta. They named this natural compound Emmenin. In collaboration with the McGill investigators and with the approval of McGill's biochemistry department, Ayerst, McKenna and Harrison, a company in Montréal, manufactured Emmenin, the first orally active female sex hormone available for clinical use.

In 1938 another group of researchers published data describing the isolation of estrogens from pregnant mares' urine. Drs Stanley Cook and Gordon Grant of Ayerst, McKenna and Harrison decided to investigate this estrogenic complex as a possible source of an orally active product. Consequently, in January 1939 the first gallon of pregnant mares' urine was processed at the company's production plant.


During the following years, Ayerst researchers determined the biologic and metabolic effects of the various estrogenic components of the new compound, which they named Premarin. They found that Premarin is not solely a natural estrogen but a mixture of 10 estrogens blended to represent the average composition of the material derived from pregnant mares urine. The extracted estrogenic substances are purified to the point that the product can be given intravenously.

As soon as Premarin became available for clinical use in 1941, physicians recognized the powerful effects inherent in this natural estrogen complex.

Hormone Therapy

There are a wide variety of types of estrogen available and a number of medication delivery systems. Pharmaceutical companies have diversified the ways estrogen is delivered and women can now choose a pill, gel, cream, skin patch, an implant or estrogen injections. A plastic ring containing estrogen can be placed into the vagina against the cervix. The type of estrogen used varies depending on the purpose. The most common type of estrogen delivery for menopausal symptoms is the skin patch, because skin metabolization of estrogen is better regulated than oral. In contrast, the pill is a very common delivery method for contraceptive estrogen.

Estrogen therapy, such as Premarin, was also approved for the prevention and control of osteoporosis. Results from some medical literature caused researchers to question broader health implications for estrogen replacement therapy. It was believed that estrogen therapy may have qualities that protect women against strokes and cardiovascular disease. Based on this belief millions of post-menopausal women were routinely prescribed estrogens or estrogen-progesterone complexes.

The Women's Health Initiative study was undertaken in the United States to follow women who were prescribed hormone replacements to determine whether there were long-term health implications to hormone use. The study was prematurely halted because a number of health problems surfaced that may have been influenced by hormone replacement. The study revealed that supplemental estrogen did not offer women protection against cardiovascular disease and may increase the risk of stroke. Subsequently millions of women across the world were instructed to stop using hormone replacement therapy. The use of hormones, including estrogen, to treat symptoms of menopause, while not abandoned, has been radically re-examined.

Currently there is great interest in and discussion of "bio-identical" hormones. Estrogen is produced in the body in three basic chemical forms: estradiol, estrone and estriol. Estrogen can also be created synthetically in a laboratory. Proponents suggest that hormones chemically derived from natural sources may be easier for the body to synthesize than standard hormones, but there is no medical research to support this contention. Natural health product and pharmaceutical companies are competing for the hormone replacement revenue and many different products are represented as the best choice. The use of "bio-identical" hormones actually refers to hormonal therapy via one of the three specific types of estrogen. There is a selection of commonly prescribed hormonal medications that use one of the three estrogen forms.