See BOXED WARNINGS.
The use of unopposed estrogens in women who have a uterus is associated with an increased risk of endometrial cancer.
1. Cardiovascular disorders.
Estrogen and estrogen/progestin therapy have been associated with an increased risk of cardiovascular events such as myocardial infarction and stroke, as well as venous thrombosis and pulmonary embolism (venous thromboembolism or VTE). Should any of these occur or be suspected, estrogens should be discontinued immediately.
Risk factors for arterial vascular disease (e.g., hypertension, diabetes mellitus, tobacco use, hypercholesterolemia, and obesity) and/or venous thromboembolism (e.g., personal history or family history of VTE, obesity, and systemic lupus erythematosus) should be managed appropriately.
a. Coronary heart disease and stroke. In the Women’s Health Initiative (WHI) study, an increase in the number of myocardial infarctions and strokes has been observed women receiving CE compared to placebo. These observations are preliminary, and the study is continuing. (See CLINICAL PHARMACOLOGY, Clinical Studies.)
In the CE/MPA substudy of WHI an increased risk of coronary heart disease (CHD) events (defined as non-fatal myocardial infarction and CHD death) was observed in women receiving CE/MPA compared to women receiving placebo (37 vs 30 per 10,000 personyears). The increase in risk was observed after the first year and persisted.
In the same substudy of WHI, an increased risk of stroke was observed in women receiving CE/MPA compared to women receiving placebo (29 vs 21 per 10,000 person-years). The increase in risk was observed after the first year and persisted.
In postmenopausal women with documented heart disease (n = 2,763, average age 66.7 years) a controlled clinical trial of secondary prevention of cardiovascular disease (Heart and Estrogen/Progestin Replacement Study; HERS) treatment with CE/MPA (0.625 mg/2.5 mg per day) demonstrated no cardiovascular benefit. During an average follow-up of 4.1 years, treatment with CE/MPA did not reduce the overall rate of CHD events in postmenopausal women with established coronary heart disease. There were more CHD events in the CE/MPA-treated group than in the placebo group in year 1, but not during the subsequent years. Two thousand three hundred and twenty one women from the original HERS trial agreed to participate in an open label extension of HERS, HERS II. Average follow-up in HERS II was an additional 2.7 years, for a total of 6.8 years overall. Rates of CHD events were comparable among women in the CE/MPA group and the placebo group in HERS, HERS II, and overall.
Large doses of estrogen (5 mg conjugated estrogens per day), comparable to those used to treat cancer of the prostate and breast, have been shown in a large prospective clinical trial in men to increase the risks of nonfatal myocardial infarction, pulmonary embolism, and thrombophlebitis.
b. Venous thromboembolism (VTE). In the Woman’s Health Initiative (WHI) study, increase in VTE has been observed in women receiving CE compared to placebo. These observations are preliminary, and the study is continuing. (See CLINICAL PHARMACOLOGY, Clinical Studies.)
In the CE/MPA substudy of WHI, a 2-fold greater rate of VTE, including deep venous thrombosis and pulmonary embolism, was observed in women receiving CE/MPA compared to women receiving placebo. The rate of VTE was 34 per 10,000 person-years in the CE/MPA group compared to 16 per 10,000 person-years in the placebo group. The increase in VTE risk was observed during the first year and persisted.
If feasible, estrogens should be discontinued at least 4 to 6 weeks before surgery of type associated with an increased risk of thromboembolism, or during periods of prolonged immobilization.
2. Malignant neoplasms.
a. Endometrial cancer. The use of unopposed estrogens in women with intact uteri has been associated with an increased risk of endometrial cancer. The reported endometrial cancer risk among unopposed estrogen users is about 2- to 12-fold greater than nonusers, and appears dependent on duration of treatment and on estrogen dose. Most studies show no significant increased risk associated with the use of estrogens for less than 1 year. The greatest risk appears associated with prolonged use, with increased risks of 15- to 24-fold for use over 5 to 10 years or more, and this risk has been shown persist at least 8 to 15 years after estrogen therapy is discontinued.
Clinical surveillance of all women taking estrogen/progestin combinations is important. Adequate diagnostic measures, including endometrial sampling when indicated, should be undertaken to rule out malignancy in all cases of undiagnosed persistent or recurring abnormal vaginal bleeding. There is no evidence that the use of natural estrogens results in a different endometrial risk profile than synthetic estrogens of equivalent estrogen dose. Adding a progestin to postmenopausal estrogen therapy has been shown to reduce the risk of endometrial hyperplasia, which may be a precursor to endometrial cancer.
b. Breast cancer. Estrogen and estrogen/progestin therapy in postmenopausal women has been associated with an increased risk of breast cancer. In the CE/MPA substudy of the Women’s Health Initiative (WHI) study, a 26% increase in invasive breast cancer (38 vs 30 per 10,000 person-years) after an average of 5.2 years of treatment was observed in women receiving CE/MPA compared to women receiving placebo. The increased risk of breast cancer became apparent after 4 years of treatment with CE/MPA. The women reporting prior postmenopausal use of estrogens and/or estrogens with progestin had higher relative risk for breast cancer associated with CE/MPA than those who had never used these hormones. (See CLINICAL PHARMACOLOGY, Clinical Studies.)
In the WHI, no increased risk of breast cancer in CE-treated women compared to placebo was reported after an average of 5.2 years of therapy. These data are preliminary and that substudy of WHI is continuing.
Epidemiologic studies have reported an increased risk of breast cancer in association with increasing duration of postmenopausal treatment with estrogens with or without a progestin. This association was reanalyzed in original data from 51 studies that involved various doses and types of estrogens, with and without progestin. In the reanalysis, an increased risk of having breast cancer diagnosed became apparent after about 5 years of continuous treatment and subsided after treatment had been discontinued for 5 years or longer. Some later studies have suggested that postmenopausal treatment with estrogens and progestin increases the risk of breast cancer more than treatment with estrogen alone.
3. Gallbladder disease. A 2- to 4-fold increase in the risk of gallbladder disease requiring surgery in postmenopausal women receiving estrogens has been reported.
4. Hypercalcemia. Estrogen administration may lead to severe hypercalcemia in patients with breast cancer and bone metastases. If hypercalcemia occurs, the drug should be stopped and appropriate measures taken to reduce the serum calcium level.
5. Visual abnormalities. Retinal vascular thrombosis has been reported in patients receiving estrogens. Discontinue medication pending examination if there is sudden partial or complete loss of vision, or a sudden onset of proptosis, diplopia, or migraine. If examination reveals papilledema or retinal vascular lesions, estrogens should be discontinued.
1. Addition of a progestin when a woman has not had a hysterectomy. Studies of the addition of a progestin for 10 or more days of a cycle of estrogen administration, or daily with estrogen in a continuous regimen, have reported a lower incidence of endometrial hyperplasia than would be induced by estrogen treatment alone. Endometrial hyperplasia may be a precursor to endometrial cancer. There are, however, possible risks that may be associated with the use of progestins with estrogens compared to estrogen-alone regimens.These include:
a. A possible increased risk of breast cancer.
b. Adverse effects on lipoprotein metabolism (e.g., lowering HDL, raising LDL)
c. Impairment of glucose metabolism.
2. Elevated blood pressure. In a small number of case reports, substantial increases blood pressure have been attributed to idiosyncratic reactions to estrogens. In a large, randomized, placebo-controlled, clinical trial, a generalized effect of estrogen therapy blood pressure was not seen. Blood pressure should be monitored at regular intervals with estrogen use.
3. Familial hyperlipoproteinemia. In patients with familial defects of lipoprotein metabolism, estrogen therapy may be associated with elevations of plasma triglycerides, leading to pancreatitis and other complications.
4.. Impaired liver function. Although topically administered estrogen therapy avoids first-pass hepatic metabolism, estrogens may be poorly metabolized in patients with impaired liver function. For patient with a history of cholestatic jaundice associated with past estrogen use or with pregnancy, caution should be exercised and in the case of recurrence, medication should be discontinued.
5. Hypothyroidism. Estrogen administration leads to increased thyroid-binding globulin (TBG) levels. Patients with normal thyroid function can compensate for the increased TBG by making more thyroid hormone, thus maintaining free T4 and T3 serum concentrations in the normal range. Patients dependent on thyroid hormone replacement therapy who are also receiving estrogens may require increased doses of their thyroid replacement therapy. These patients should have their thyroid function monitored in order to maintain their free thyroid hormone levels in an acceptable range.
6. Fluid retention. Because estrogens may cause some degree of fluid retention, conditions that might be influenced by this factor, such as a cardiac or renal dysfunction, warrant careful observation when estrogens are prescribed.
7. Hypocalcemia. Estrogens should be used with caution in individuals with severe hypocalcemia.
8. Ovarian cancer. Use of estrogen-only products, in particular for ten or more years, has been associated with an increased risk of ovarian cancer in some epidemiological studies. Other studies did not show a significant association. Data are insufficient to determine whether there is an increased risk with combined estrogen/progestin therapy in postmenopausal women.
9.. Exacerbation of endometriosis. Endometriosis may be exacerbated with administration of estrogens.
A few cases of malignant transformation of residual endometrial implants have been reported in women treated post-hysterectomy with estrogen-only therapy. For patients known to have residual endometriosis post-hysterectomy, the addition of progestin should be considered.
10.. Exacerbation of other conditions. Estrogens may cause an exacerbation of asthma, diabetes mellitus, epilepsy, migraine, porphyria, systemic lupus erythematosus, and hepatic hemangiomas and should be used with caution in patients with these conditions.
11. Application of sunscreen. Estrasorb® should not be used in close proximity sunscreen application because estradiol absorption may be increased. (See CLINICAL PHARMACOLOGY, Pharmacokinetics, Absorption.)
B. Patient Information
Physicians are advised to discuss the contents of the PATIENT INFORMATION leaflet with patients for whom they prescribe Estrasorb®.
C. Laboratory Tests
Estrogen administration should be initiated at the lowest dose approved for the indication and then guided by clinical rather than by serum hormone levels (e.g., estradiol, FSH).
D. Drug/Laboratory Test Interactions
1 . Accelerated prothrombin time, partial thromboplastin time, and platelet aggregation time; increased platelet count; increased factors II, VII antigen, VIII antigen, VIII coagulant activity, IX, X, XII, VII-X complex, II-VII-X complex, and beta-thromboglobulin; decreased levels of antifactor Xa and antithrombin III; decreased antithrombin III activity; increased levels of fibrinogen and fibrinogen activity; increased plasminogen antigen and activity.
2 . Increased thyroid-binding globulin (TBG) levels leading to increased circulating total thyroid hormone, as measured by protein-bound iodine (PBI), T4 levels (by column or by radioimmunoassay) or T3 levels by radioimmunoassay. T3 resin uptake is decreased, reflecting the elevated TBG. Free T4 and free T3 concentrations are unaltered. Patients on thyroid replacement therapy may require higher doses of thyroid hormone.
3 . Other binding proteins may be elevated in serum (i.e., corticosteroid binding globulin, and sex hormone binding globulin), leading to increased circulating corticosteroids and sex steroids, respectively. Free or biologically active hormone concentrations are unchanged. Other plasma proteins may be increased (angiotensinogen/renin substrate, alpha-1-antitrypsin, ceruloplasmin).
4. Increased plasma HDL and HDL-2 cholesterol subfraction concentrations, reduced LDL cholesterol concentration, and increased triglycerides levels.
5 . Impaired glucose tolerance.
6 . Reduced response to metyrapone test.
E. Carcinogenesis, Mutagenesis, Impairment of Fertility
Long-term continuous administration of natural and synthetic estrogens in certain animal species increases the frequency of carcinomas of the breast, uterus, cervix, vagina, testis, and liver (See BOXED WARNINGS, CONTRAINDICATIONS, and WARNINGS.)
Estrasorb® should not be used during pregnancy. (See CONTRAINDICATIONS.)
G. Nursing Mothers
Estrogen administration to nursing mothers has been shown to decrease the quantity and quality of the milk. Detectable amounts of estrogens have been identified in the milk of mothers receiving this drug. Caution should be exercised when Estrasorb® is administered to a nursing woman.
H. Pediatric Use
Estrogen therapy has been used for the induction of puberty in adolescents with some forms of pubertal delay. Safety and effectiveness in pediatric patients have not otherwise been established.
I. Geriatric Use
There have not been sufficient numbers of geriatric patients involved in studies utilizing Estrasorb® to determine whether those over 65 years of age differ from younger subjects in their response to Estrasorb®.