What Is in the Drug Premarin?

Premarin is a prescription drug that contains a mixture of estrogen hormones, also called conjugated estrogens. The estrogens are not synthetic but derived from a natural source. Premarin is in a class of drugs used for hormone replacement therapy and is most often used to treat the symptoms associated with menopause. It is also used for the prevention of postmenopausal osteoporosis. Premarin is available as an oral tablet and a cream and is dispensed in several different strengths. Estrogen-only hormone therapy is usually indicated for women without a uterus; women with a uterus typically benefit from combined estrogen-plus-progestin hormone therapy.

Ingredients

• Premarin is a nonsynthetic, organic mixture of estrogen hormones. It contains the hormones estrone, equilin, 17 alpha-dihydroequilin, 17 alpha-estradiol, equilenin and 17 alpha-dihydroequilenin. Additionally, Premarin contains several inactive ingredients to act as preservatives and fillers in the product.

Significance

• Menopause and osteoporosis are two conditions that Premarin is used to treat. Estrogen is a sex hormone normally produced by the ovaries. Menopause occurs when a woman's ovaries stop making estrogen. This natural process generally occurs between the ages of 45 and 55 years. Menopause may also result from the surgical removal of the ovaries before natural menopause occurs.
  Osteoporosis is the loss of bone mass and results in an increased fracture risk. Bone loss occurs throughout adulthood but accelerates after menopause due to the decrease in estrogen.

Function

• During menopause, many women experience uncomfortable symptoms due to the decreasing estrogen levels, including hot flashes, vaginal dryness and mood-related symptoms. Estrogen replacement therapy relieves these symptoms in many women. Also, estrogen replacement therapy can improve bone density in women at significant risk for osteoporosis.

Drug Interactions

• Premarin may interact with several common medications, foods and herbal supplements. Hydrocortisone and anticoagulants increase the effect of estrogen. Anticonvulsants, as well as Rifampin, Nelfinavir and Ritonavir, decrease the effect of estrogen. Women on Premarin should avoid the routine use of ethanol, St. John's Wort, black cohosh, dong quai, red clover, saw palmetto and ginseng.

Risks

• Premarin may cause headaches, breast pain, irregular vaginal bleeding, stomach cramps and bloating, nausea and vomiting, hair loss, fluid retention and vaginal yeast infections. These side effects are fairly common, but not serious, and usually lessen with time.
  More serious side effects of Premarin treatment include cancer of the breast, uterus, or ovaries; blood clots leading to heart attack or stroke; high blood pressure; high blood sugar; and liver problems. These side effects occur infrequently, but warning signs, including breast lumps, dizziness, changes in speech or vision, chest pain, shortness of breath, or yellowing of the skin or eyes, should be reported to your health care provider immediately.

Expert Insight

• Influential investigations of estrogen-only hormone therapy during the Women's Health Initiative studies showed an increased risk of stroke, deep vein thrombosis, heart attack and invasive breast cancer in postmenopausal women. Additionally, other treatment options are preferred as first-line therapy over Premarin for menopausal symptoms and prevention of osteoporosis in most women. These options, and their risks and benefits, should be discussed with your health care provider before beginning treatment. To mitigate the risks associated with Premarin, estrogen therapy should always be prescribed at the lowest effective dose for the shortest possible duration.