Drug Name

Premarin (Conjugated Estrogens)

Drug Uses

Conjugated estrogens are used for treating the symptoms of menopause including hot flashes, vaginal dryness, and vaginal atrophy. They also are used as therapy when the body does not produce enough estrogen due to castration, ovarian failure or underdevelopment of hormone-secreting organs (hypogonadism). Conjugated estrogens also may be beneficial in treating advanced prostate and breast cancer. Although estrogens are approved for treating osteoporosis, other drugs usually are prescribed for this purpose.

How Taken

Tablets: 0.3, 0.45, 0.625, 0.9, and 1.25 mg. To minimize side effects, the lowest effective oral dose of conjugated estrogens is used. The usual starting dose for treating symptoms associated with menopause and for preventing postmenopausal osteoporosis is 0.3 mg/day. The dose should be increased based on the response of patients' symptoms.

Hypogonadism is treated with doses of 0.3 mg or 0.625 daily with a cyclical interval of three weeks on treatment followed by one week off treatment. The dose for women who have been castrated or have ovarian failure is 1.25 mg daily in a cyclical interval of three weeks on treatment and one week off treatment. (In reality, most women take estrogens continuously since during the week off treatment, symptoms return because of the lack of estrogen.) For treatment of breast cancer the recommended dose is 10 mg daily for three months.

Drug Class and Mechanism

Estrogens are one of the two major classes of female hormones. (Progestins comprise the second major class.) Estrogens are used primarily to treat the symptoms of menopause and states in which there is a deficiency of estrogen, for example, in women who have had their ovaries removed.

Conjugated equine estrogens are a mixture of several different estrogens that are derived from the urine of pregnant mares. Estrogens have widespread effects on many tissues in the body. Estrogens cause growth and development of the female sexual organs and maintain female sexual characteristics such as the growth of underarm and pubic hair and the shape of body contours and skeleton. Estrogens also increase secretions from the cervix and growth of the inner lining of the uterus (endometrium).

Missed Dose

Take the missed dose as soon as you remember then return to your regular dosing schedule. Do not take a double dose of this medication unless otherwise directed by your doctor.

Storage

Conjugated equine estrogens should be stored at room temperature between 15-30 degrees C (59-77 degrees F).

Warnings/Precautions

There are no restrictions on food, beverages, or activity while taking conjugated estrogens unless your doctor directs otherwise. Estrogens should not be given to pregnant women due to the risk of harm to the fetus. Estrogens are secreted in breast milk and cause unpredictable effects in the infant. They should not be taken by women who are breast-feeding.

Possible Side Effects

The most common side effects of conjugated estrogens are headache, nausea, back pain, joint pain and vaginal bleeding. Patients may also experience vaginal spotting, loss of periods or excessively prolonged periods, breast pain, breast enlargement and an increase or decrease in sexual drive. Effects of estrogen on the skin include rash, and melasma (tan or brown patches) that may develop on the forehead, cheeks, or temples and may persist even after estrogens are stopped. In the eyes, conjugated estrogens may cause an increase in the curvature of the cornea, and patients with contact lenses may develop intolerance to their lenses.

There is an increased risk of cholesterol gallstones among men and women taking estrogens. Estrogens can inhibit the flow of bile from the liver (cholestasis) and uncommonly cause jaundice.

More Information

• Conjugated estrogens increase the risk of developing a condition (endometrial hyperplasia) that may lead to cancer of the lining of the uterus. Taking progestins, another hormone drug, with conjugated estrogens lowers the risk of developing this condition. Therefore, if your uterus has not been removed, your doctor may prescribe a progestin for you to take together with the estrogen. Visit your doctor regularly and report any unusual vaginal bleeding right away.
• Treatment with conjugated estrogens may increase the risk of heart attack, stroke, breast cancer, and blood clots in the lungs or legs. Because of these risks, conjugated estrogens should be prescribed at the lowest effective dose, for the shortest amount of time necessary.
• If you experience any of the following serious side effects, stop taking conjugated estrogens and seek emergency medical attention:
  • an allergic reaction (difficulty breathing; closing of the throat; swelling of the lips, tongue, or face; or hives);
  • shortness or breath or pain in the chest;
  • a painful, red, or swollen leg;
  • abnormal vaginal bleeding;
  • pain, swelling, or tenderness in the abdomen;
  • severe headache or vomiting, dizziness, faintness or changes in vision or speech;
  • yellowing of the skin or eyes; or
  • a lump in a breast.
• Other, less serious side effects may be more likely to occur. Continue to take conjugated estrogens and talk to your doctor if you experience
  • decreased appetite, nausea, or vomiting;
  • swollen or tender breasts;
  • acne or skin color changes;
  • decreased sex drive;
  • migraine headaches or dizziness;
  • water retention (swollen hands, feet, or ankles);
  • problems with wearing contact lenses;
  • depression; or
  • changes in menstrual cycle or breakthrough bleeding.
• Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.