DRUG INDEX
GENERIC NAME: conjugated estrogens BRAND NAME: Premarin
DRUG CLASS AND MECHANISM: Conjugated estrogens are a mixture of several different estrogens. The mixture is derived from equine (horse) urine. Estrogens have widespread effects on many tissues in the body. Estrogens, when taken alone or in combination with a progestin, have been shown to reduce the risk for hip fracture due to osteoporosis by 25% and the risk of heart attack (myocardial infarction) and stroke by 40-50%. Estrogens cause growth and development of female sex organs and the maintenance of sexual characteristics, including growth of underarm and pubic hair and shaping of body contours and skeleton. Estrogens also increase secretions from the cervix and growth of the inner lining of the uterus (endometrium). Estrogens reduce LDL-cholesterol ("bad" cholesterol) and increase HDL-cholesterol ("good" cholesterol) concentrations. Conjugated estrogen products were approved by the FDA in 1938.
PRESCRIPTION: yes
GENERIC AVAILABLE: no
PREPARATIONS: Tablets of 0.3, 0.45, 0.625, 0.9, 1.25, and 2.5 mg.
STORAGE: Tablets should be stored between 2°C (36°F) and 30°C (86°F).
PRESCRIBED FOR: Conjugated estrogens are prescribed for symptomatic treatment of the symptoms associated with menopause ( for example, hot flashes and vaginal dryness), prevention of bone fractures associated with osteoporosis, reducing of risk of heart attacks and strokes, dysfunctional (excessive and painful) uterine bleeding, and, occasionally, prostate cancer .
DOSING: Conjugated estrogens are usually prescribed as a single daily dose.
DRUG INTERACTIONS: Estrogens can inhibit the metabolism of cyclosporine, resulting in increased cyclosporine blood levels. These increased blood levels can result in kidney and/or liver damage. If this combination cannot be avoided, cyclosporine concentrations should be monitored, and the dose of cyclosporine can be adjusted to assure that its blood levels are not elevated.
Estrogens appear to increase the risk of liver disease in patients receiving dantrolene through an unknown mechanism. Women over 35 years of age and those with a history of liver disease are especially at risk. Estrogens increase the liver's ability to manufacture clotting factors. Because of this, patients receiving warfarin (Coumadin) need to be monitored for loss of anticoagulant (blood thinning) effect if treatment with an estrogen is instituted.
Rifampin, barbiturates, carbamazepine (Tegretol), griseofulvin, phenytoin (Dilantin) and primidone, can all increases the elimination of estrogen by enhancing the liver's ability to metabolize it. Concurrent use of these medications with estrogens may result in reduction of the beneficial effects of estrogens.
PREGNANCY: Estrogens should not be taken during pregnancy due to an increased risk of fetal abnormalities.
NURSING MOTHERS: Estrogens are secreted in breast milk and cause unpredictable effects in the infant. Therefore, estrogens generally should be avoided during breast-feeding.
SIDE EFFECTS: Among the most common endocrine side effects are uterine bleeding or spotting, loss of periods or excessively prolonged periods, breast pain, breast enlargement, and changes in sexuality (increases or decreases in libido). There is an increased risk of cholesterol gallstones among men and women taking estrogens. Migraine headaches have been associated with estrogen therapy. Estrogens can cause sodium and fluid retention. Melasma, tan or brown patches, may develop on the forehead, cheeks, or temples. These may persist even after the estrogen is stopped. Conjugated estrogens may cause an increase in the curvature of the cornea, and patients with contact lenses may develop intolerance to their lenses. Estrogens can inhibit the flow of bile from the liver (a condition called cholestasis) and even cause jaundice .
Blood clots are occasional but potentially serious complications of estrogen therapy and are dose-related; cigarette smokers are at a higher risk. Therefore, patients requiring estrogen therapy are encouraged strongly to quit smoking .
Estrogens can promote a buildup of the lining of the uterus (called endometrial hyperplasia) and increase the risk of endometrial cancer. At diagnosis, endometrial cancers in women receiving estrogens are generally at an earlier stage and a lower grade than in those who have not taken estrogens. Survival also is better in women with endometrial cancer who have taken estrogens. The addition of a progestin to estrogen therapy prevents the development of endometrial cancer.
Conflicting data exists on the association between estrogens and breast cancer. There may be a small increase in risk. The effect of adding a progestin on the risk of estrogen-induced breast cancer is unclear.
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