<unk>  <unk> s), or<unk>  equine estrogens <unk> Es), sold under the brand name Premarin among others, is an estrogen medication which is used in menopausal hormone therapy and for various other indications. It is a mixture of the sodium salts of estrogen<unk>  found in horses, such as estrone sulfate and equilin sulfate.<unk> Es are available in the form of both natural preparations manufactured from the urine of pregnant mares and fully synthetic replications of the natural preparations. They are formulated both alone and in combination with progestins such as medroxyprogesterone acetate.<unk> Es are usually taken by mouth, but can also be given by application to the skin or vagina as a cream or by injection into a blood vessel or muscle. Side effects of<unk> Es include breast tenderness and enlargement, headache, fluid retention, and nausea among others. It may increase the risk of endometrial hyperplasia and endometrial cancer in women with an intact uterus if it is not taken together with a progestogen like progesterone. The medication may also increase the risk of blood clots, cardiovascular disease, and, when combined with most progestogens, breast cancer.<unk> Es are estrogens, or agonists of the estrogen receptor, the biological target of estrogens like estradiol. Compared to estradiol,<unk> rtain estrogens in<unk> Es are more resistant to metabolism, and the medication shows relatively increased effects in<unk> rtain parts of the body like the liver. This results in an increased risk of blood clots and cardiovascular problems with<unk> Es relative to estradiol. Premarin, the major brand of<unk> Es in use, is manufactured by Pfizer and was first marketed in 1941 in Canada and in 1942 in the United States. It is the most commonly used form of estrogen in menopausal hormone therapy in the United States. However, it has begun to fall out of favor relative to bioidentical estradiol, which is the most widely used form of estrogen in Europe for menopausal hormone therapy.<unk> Es are available widely throughout the world. An estrogen preparation very similar to<unk> Es but differing in source and composition is esterified estrogens. In 2017, it was the 206th most commonly prescribed medication in the United States, with more than two million prescriptions.
Conjugated estrogens
Phytoestrogen
Xenoestrogen
Antiestrogen
Esterified estrogens
Phytoprogestogen
Tissue-selective estrogen complex
Antiprogestogen