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ESTROGENS INCREASE THE RISK OF ENDOMETRIAL CANCER
Close clinical surveillance of all women taking estrogens 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 at equivalent estrogen doses. (See WARNINGS, Malignant neoplasms, Endometrial cancer .)
CARDIOVASCULAR AND OTHER RISKS
Estrogens with or without progestins should not be used for the prevention of cardiovascular disease or dementia. (See CLINICAL STUDIES and WARNINGS, Cardiovascular disorders , and Dementia .)
The Women's Health Initiative (WHI) estrogen alone substudy reported increased risks of stroke and deep vein thrombosis (DVT) in postmenopausal women (50 to 79 years of age) during 6.8 years and 7.1 years, respectively, of treatment with oral conjugated estrogens (CE 0.625 mg) per day relative to placebo. (See CLINICAL STUDIES and WARNINGS, Cardiovascular disorders .)
The estrogen plus progestin WHI substudy reported increased risk of myocardial infarction, stroke, invasive breast cancer, pulmonary emboli, and deep vein thrombosis in postmenopausal women (50 to 79 years of age) during 5.6 years of treatment with oral conjugated estrogens (CE 0.625 mg) combined with medroxyprogesterone acetate (MPA 2.5 mg) per day relative to placebo. (See CLINICAL STUDIES and WARNINGS, Cardiovascular disorders and Malignant neoplasms, Breast cancer .)
The Women's Health Initiative Memory Study (WHIMS), a substudy of the WHI study, reported increased risk of developing probable dementia in postmenopausal women 65 years of age or older during 5.2 years of treatment with CE 0.625 mg alone and during 4 years of treatment with CE 0.625 mg combined with MPA 2.5 mg relative to placebo. It is unknown whether this finding applies to younger postmenopausal women. (See CLINICAL STUDIES and WARNINGS, Dementia and PRECAUTIONS, Geriatric Use .)
Other doses of conjugated equine estrogens with medroxyprogesterone acetate and other combinations and dosage forms of estrogens and progestins were not studied in the WHI clinical trials and, in the absence of comparable data, these risks should be assumed to be similar. Because of these risks, estrogens with or without progestins should be prescribed at the lowest effective doses and for the shortest duration consistent with treatment goals and risks for the individual woman.
Elestrin (estradiol gel) contains 0.06% estradiol in a hydroalcoholic gel base. The gel is applied onto the skin in a thin layer. The recommended area of application is the upper arm to shoulder (approximately 320 cm). One pump actuation delivers Elestrin in a unit dose of 0.87 g, which contains 0.52 mg of estradiol. The 0.87 g dose provides systemic delivery of 0.0125 mg of estradiol daily. The 1.7 g dose, two pump actuations, provides systemic delivery of 0.0375 mg daily.
Estradiol is a white crystalline powder, chemically described as estra-1,3,5(10)-triene-3,17-diol, (17β)-. It has a molecular formula of CHO•½HO and molecular weight of 281.4.
The structural formula is:
The active component of Elestrin is estradiol. The remaining components of the gel (ethanol, propylene glycol, diethylene glycol monoethyl ether, carbomer 940, triethanolamine, edetate disodium, and purified water) are pharmacologically inactive.
Endogenous estrogens are largely responsible for the development and maintenance of the female reproductive system and secondary sexual characteristics. Although circulating estrogens exist in a dynamic equilibrium of metabolic interconversions, estradiol is the principal intracellular human estrogen and is substantially more potent than its metabolites, estrone and estriol, at the receptor level.
The primary source of estrogen in normally cycling adult women is the ovarian follicle, which secretes 70 to 500 mcg of estradiol daily, depending on the phase of the menstrual cycle. After menopause, most endogenous estrogen is produced by conversion of androstenedione, secreted by the adrenal cortex, to estrone by peripheral tissues. Thus, estrone and the sulfate-conjugated form, estrone sulfate, are the most abundant circulating estrogens in postmenopausal women.
Estrogens act through binding to nuclear receptors in estrogen-responsive tissues. To date, two estrogen receptors have been identified. These vary in proportion from tissue to tissue.
Circulating estrogens modulate the pituitary secretion of the gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH) through a negative feedback mechanism. Estrogens act to reduce the elevated levels of these hormones seen in postmenopausal women.
Steady-state serum concentrations of estradiol are achieved in approximately 3 days following daily application of Elestrin to the upper arm.
Pharmacokinetic parameters for estradiol on Day 14 following daily application of 0.87 g or 1.7 g of Elestrin are summarized in Table 1 . The nominal mean delivery rates of estradiol using the baseline-adjusted average serum concentrations from pharmacokinetic studies using 0.87 g/day and 1.7 g/day are 0.012 mg/day and 0.041 mg/day, respectively.
Mean concentrations of estradiol over a 24-hour period on Day 14 are shown in Figure 1.
Application of sunscreen 10 minutes before application of Elestrin increased the exposure to estradiol by approximately 55%. No significant change in estradiol exposure was observed when sunscreen was applied 25 minutes after application of Elestrin. In the same study, prolonged (7 days) concomitant application of sunscreen to the site of Elestrin application increased exposure to estradiol by about 2-fold, regardless of whether it was applied before or after application of Elestrin.
0.87 g Elestrin®
(0.52 mg/d Estradiol)
1.7 g Elestrin®
(1.04 mg/d Estradiol)
|Tmax (h)a||18 (1 – 20)||4 (1 – 20)|
The distribution of exogenous estrogens is similar to that of endogenous estrogens. Estrogens are widely distributed in the body and are generally found in higher concentrations in the sex hormone target organs. Estrogens circulate in blood largely bound to sex hormone binding globulin (SHBG) and albumin.
Exogenous estrogens are metabolized in the same manner as endogenous estrogens. Circulating estrogens exist in a dynamic equilibrium of metabolic interconversions. These transformations take place mainly in the liver. Estradiol is converted reversibly to estrone, and both can be converted to estriol, which is the major urinary metabolite. Estrogens also undergo enterohepatic recirculation via sulfate and glucuronide conjugation in the liver, biliary secretion of conjugates into the intestine, and hydrolysis in the intestine followed by reabsorption.
In postmenopausal women, a significant proportion of the circulating estrogens exist as sulfate conjugates, especially estrone sulfate, which serves as a circulating reservoir for the formation of more active estrogens.
Estradiol, estrone and estriol are excreted in the urine along with glucuronide and sulfate conjugates.
Elestrin has been studied only in postmenopausal women. No pharmacokinetic studies were conducted in special populations, including patients with renal or hepatic impairment or any other special populations.
In vitro and in vivo studies have shown that estrogens are metabolized partially by cytochrome P450 3A4 (CYP3A4). Therefore, inducers or inhibitors of CYP3A4 may affect estrogen drug metabolism. Inducers of CYP3A4, such as St. John's Wort preparations (Hypericum perforatum), phenobarbital, carbamazepine, and rifampin, may reduce plasma concentrations of estrogens, possibly resulting in a decrease in therapeutic effects and/or changes in the uterine bleeding profile. Inhibitors of CYP3A4, such as erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir, and grapefruit juice, may increase plasma concentrations of estrogens and result in side effects.
The potential for estradiol transfer between treated postmenopausal female subjects and their untreated male partners was evaluated. Two and 8 hours after women applied 2.6 g Elestrin to one arm (12 women per time point), they engaged in direct arm-to-arm contact with a male partner for 5 minutes. No significant changes in estradiol pharmacokinetic parameters were observed in the male partners after contact.
Less than 10% of the estradiol dose was measured on the skin at 2 and 8 hours after application. After washing the application site with soap and water at 8 hours after application, about 1% of the dose of estradiol was measurable.
A randomized, double-blind, placebo-controlled clinical trial evaluated the efficacy of 12-week treatment with three different daily doses of Elestrin for the treatment of vasomotor symptoms in 484 postmenopausal women between 28 and 74 years of age (mean 54 years; 83-88% Caucasian per group) who had at least 60 moderate-to-severe hot flushes per week at baseline. Subjects applied placebo, Elestrin 0.87 g (0.52 mg estradiol), 1.7 g (1.04 mg estradiol), or 2.6 g (1.56 mg estradiol) once daily to the upper arm. Reduction in both the frequency and severity of moderate-to-severe hot flushes was statistically significant for the Elestrin 1.7 g/day dose compared to placebo at week 4. Statistically significant reductions in both the frequency and severity of moderate-to-severe hot flushes when compared to placebo were delayed for the Elestrin 0.87 g/day dose to week 5. Both the 0.87 g/day and 1.7 g/day doses were statistically significant compared to placebo at week 12. The reductions in frequency and severity are shown in Table 2 .
|Number of Daily Hot Flushes|
|Baseline (Mean ± SD)b||13.5 ± 4.5||13.3± 4.6||13.1 ± 6.5|
|Mean Change:||Week 4||-5.1||-6.5#||-8.0***|
|Daily Hot Flush Severityc|
|Baseline (Mean ± SD)b||2.4 ± 0.3||2.4 ± 0.3||2.4 ± 0.3|
|Mean Change:||Week 4||-0.2||-0.5#||-0.7***|
The Women's Health Initiative (WHI) enrolled approximately 27,000 predominantly healthy postmenopausal women to assess the risks and benefits of either the use of oral conjugated estrogens (CE 0.625 mg) alone per day or in combination with medroxyprogesterone acetate (MPA 2.5 mg) per day compared to placebo in the prevention of certain chronic diseases. The primary endpoint was the incidence of coronary heart disease (CHD) (nonfatal myocardial infarction (MI), silent MI and CHD death), with invasive breast cancer as the primary adverse outcome studied. A "global index" included the earliest occurrence of CHD, invasive breast cancer, stroke, pulmonary embolism (PE), endometrial cancer (only in the estrogen plus progestin substudy), colorectal cancer, hip fracture, or death due to other cause. The study did not evaluate the effects of CE or CE/MPA on menopausal symptoms.
The estrogen alone substudy was stopped early because an increased risk of stroke was observed. Results of the estrogen alone substudy, which included 10,739 women (average age of 63 years, range 50 to 79; 75.3% White, 15.1% Black, 6.1% Hispanic, 3.6% Other), after an average follow-up of 6.8 years are presented in Table 3 .
For those outcomes included in the WHI "global index," that reached statistical significance, the absolute excess risk per 10,000 women-years in the group treated with CE 0.625 mg alone were 12 more strokes, while the absolute risk reduction per 10,000 women-years was 6 fewer hip fractures. The absolute excess risk of events included in the "global index" was a nonsignificant 2 events per 10,000 women-years. There was no difference between the groups in terms of all-cause mortality. (See BOXED WARNINGS, WARNINGS, and PRECAUTIONS .)
The CE/MPA substudy was also stopped early because, according to predefined stopping rule, the increased risk of breast cancer and cardiovascular events exceeded the specified benefits included in the "global index." Results of the CE/MPA substudy, which included 16,608 women (average age of 63 years, range 50 to 79; 83.9% White, 6.8% Black, 5.4% Hispanic, 3.9% Other) after an average follow-up of 5.6 years, are presented in Table 4 :
For those outcomes included in the WHI "global index" that reached statistical significance after 5.6 years of follow-up, the absolute excess risks per 10,000 women-years in the group treated with CE/MPA were 6 more CHD events, 7 more strokes, 10 more PEs, and 8 more invasive breast cancers, while the absolute risk reductions per 10,000 women-years were 7 fewer colorectal cancers and 5 fewer hip fractures. The absolute excess risk of events included in the "global index" was 19 per 10,000 women-years (RR 1.15, 95% nCI 1.03-1.28). (See BOXED WARNINGS, WARNINGS, and PRECAUTIONS .)
CE vs. Placebo
n = 5,429
n = 5,310
|Absolute Risk per 10,000 Women-Years|
|CHD eventsc||0.95 (0.79-1.16)||56||53|
|Non-fatal MI c||0.91 (0.73-1.14)||43||40|
|CHD death c||1.01 (0.71-1.43)||16||16|
|Invasive breast cancerc||0.80 (0.62-1.04)||34||28|
|Deep vein thrombosisc,e||1.47 (1.06-2.06)||15||23|
|Pulmonary embolismc||1.37 (0.90-2.07)||10||14|
|Colorectal cancerd||1.08 (0.75-1.55)||16||17|
|Hip fractured||0.61 (0.41-0.91)||17||11|
|Vertebral fracturesd,e||0.62 (0.42-0.93)||17||11|
|Total fracturesd,e||0.70 (0.63-0.79)||195||139|
|Death due to other causesd,f||1.08 (0.88-1.32)||50||53|
|Overall mortalityd,e||1.04 (0.88-1.22)||78||81|
|Global indexd,g||1.01 (0.91-1.12)||190||192|
CE/MPA vs. Placebo
(95% nCIb )
n = 8,102
n = 8,506
|Absolute Risk per 10,000 Women-Years|
|CHD events||1.24 (1.00-1.54)||33||39|
|Non-fatal MI||1.28 (1.00-1.63)||25||31|
|CHD death||1.10 (0.70-1.75)||8||8|
|Invasive breast cancerc||1.24 (1.01-1.54)||33||41|
|All Stroke||1.31 (1.02-1.68)||24||31|
|Ischemic Stroke||1.44 (1.09-1.90)||18||26|
|Deep vein thrombosis||1.95 (1.43-2.67)||13||26|
|Pulmonary embolism||2.13 (1.45-3.11)||8||18|
|Invasive Colorectal cancer||0.56 (0.38-0.81)||16||9|
|Endometrial cancer||0.81 (0.48-1.36)||7||6|
|Cervical cancer||1.44 (0.47-4.42)||1||2|
|Hip fracture||0.67 (0.47-0.96)||16||11|
|Vertebral fractures||0.65 (0.46-0.92)||17||11|
|Lower arm/wrist fractures||0.71 (0.59-0.85)||62||44|
|Total fractures||0.76 (0.69-0.83)||199||152|
The estrogen-alone Women's Health Initiative Memory Study (WHIMS), a substudy of the WHI, enrolled 2,947 predominantly healthy postmenopausal women 65 years of age and older (45% were aged 65 to 69 years, 36% were 70 to 74 years, and 19% were 75 years of age and older) to evaluate the effects of conjugated estrogens (CE 0.625 mg) on the incidence of probable dementia (primary outcome) compared with placebo.
After an average follow-up of 5.2 years, 28 women in the CE-alone group (37 per 10,000 women-years) and 19 in the placebo group (25 per 10,000 women-years) were diagnosed with probable dementia. The relative risk of probable dementia in the CE-alone group was 1.49 (95% confidence interval [CI], 0.83-2.66) compared to placebo. It is unknown whether these findings apply to younger postmenopausal women. (See BOXED WARNINGS, WARNINGS, Dementia, and PRECAUTIONS, Geriatric Use .)
The CE/MPA WHIMS substudy enrolled 4,532 predominantly healthy postmenopausal women 65 years of age and older (47% were age 65 to 69 years, 35% were 70 to 74 years, and 18% were 75 years of age and older) to evaluate the effects of conjugated estrogens (CE 0.625 mg) plus medroxyprogesterone acetate (MPA 2.5 mg) on the incidence of probable dementia (primary outcome) compared with placebo.
After an average follow-up of 4 years, 40 women in the CE/MPA group (45 per 10,000 women-years) and 21 in the placebo group (22 per 10,000 women-years) were diagnosed with probable dementia. The relative risk of probable dementia in the hormone therapy group was 2.05 (95% CI, 1.21-3.48) compared to placebo.
When data from the two populations were pooled as planned in the WHIMS protocol, the reported overall relative risk for probable dementia was 1.76 (95% CI, 1.19-2.60). Differences between groups became apparent in the first year of treatment. It is unknown whether these findings apply to younger postmenopausal women. (See BOXED WARNING and WARNINGS, Dementia , and PRECAUTIONS, Geriatric Use .)
Elestrin 0.87 g/day and 1.7 g/day are indicated in the:
Treatment of moderate-to-severe vasomotor symptoms associated with menopause.
Estrogen products, including Elestrin, should not be used in women with any of the following conditions:
See BOXED WARNINGS
Estrogen-alone therapy has been associated with an increased risk of stroke and deep vein thrombosis (DVT).
Estrogen plus progestin therapy has been associated with an increased risk of myocardial infarction as well as stroke, venous thrombosis and pulmonary embolism. Should any of these events 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 VTE (e.g., personal history or family history of VTE, obesity, and systemic lupus erythematosus) should be managed appropriately.
In the WHI estrogen-alone substudy, a statistically significant increased risk of stroke was reported in women receiving CE 0.625 mg daily compared to placebo (44 versus 32 per 10,000 women-years). The increase in risk was observed in year 1 and persisted. (See CLINICAL STUDIES.)
In the CE/MPA substudy of WHI, a statistically significant increased risk of stroke was reported in women receiving CE/MPA daily compared to women receiving placebo (31 versus 24 per 10,000 women-years). The increase in risk was demonstrated after the first year and persisted.
In the estrogen-alone substudy of WHI, no overall effect on coronary heart disease (CHD) events (defined as nonfatal myocardial infarction (MI), silent MI and CHD death) was reported in women receiving estrogen alone compared to placebo. (See CLINICAL STUDIES.)
In the estrogen plus progestin substudy of WHI, no statistically significant increase of CHD events was reported in women receiving CE/MPA compared to women receiving placebo (39 versus 33 per 10,000 women-years). An increase in relative risk was demonstrated in year one, and a trend toward decreasing relative risk was reported in years 2 through 5.
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. Participation in an open label extension of the original HERS trial (HERS II) was agreed to by 2,321 women. 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 equine 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 risk of nonfatal myocardial infarction, pulmonary embolism, and thrombophlebitis.
In the estrogen-alone substudy of WHI, the risk of VTE (DVT and pulmonary embolism [PE]) was reported to be increased for women receiving CE compared to placebo (30 versus 22 per 10,000 women-years), although only the increased risk of DVT reached statistical significance (23 versus 15 per 10,000 women-years). The increase in VTE risk was demonstrated during the first two years. (See CLINICAL STUDIES.)
In the CE/MPA substudy of WHI, a statistically significant two-fold greater rate of VTE was reported in women receiving CE/MPA compared to women receiving placebo (35 versus 17 per 10,000 women-years). Statistically significant increases in risk for both DVT (26 versus 13 per 10,000 women-years) and PE (18 versus 8 per 10,000 women-years) were also demonstrated. The increase in VTE risk was observed during the first year and persisted. (See CLINICAL STUDIES.)
If feasible, estrogens should be discontinued at least 4 to 6 weeks before surgery of the type associated with an increased risk of thromboembolism, or during periods of prolonged immobilization.
The use of unopposed estrogens by 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 times greater than in non-users, and appears dependent on duration of treatment and on estrogen dose. Most studies show no significant increased risk associated with use of estrogens for less than 1 year. The greatest risk appears associated with prolonged use, with an increased risk of 15- to 24-fold for 5 to 10 years or more. This risk has been shown to persist for 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 estrogen therapy has been shown to reduce the risk of endometrial hyperplasia, which may be a precursor to endometrial cancer.
In a 12-week clinical trial, one case of complex hyperplasia with atypia was reported in the Elestrin 1.7 g/day dose.
The use of estrogens and progestins by postmenopausal women has been reported to increase the risk of breast cancer. The most important randomized clinical trial providing information about this issue is the Women's Health Initiative (WHI) (See CLINICAL STUDIES ). The results from observational studies are generally consistent with those of the WHI clinical trial and report no significant variation in the risk of breast cancer among different estrogens or progestins, doses, or routes of administration.
In the estrogen-alone substudy of WHI, after an average of 7.1 years of follow-up, CE (0.625 mg daily) was not associated with an increased risk of invasive breast cancer (RR 0.80, 95% nCI 0.62-1.04).
The CE/MPA substudy of WHI study reported an increased risk of breast cancer in women who took CE/MPA for a mean follow-up of 5.6 years. Observational studies have also reported an increased risk for estrogen/progestin combination therapy, and a smaller increased risk for estrogen-alone therapy, after several years of use. In the WHI trial and from observational studies, the excess risk increased with duration of use. From observational studies, the risk appeared to return to baseline in about 5 years after stopping treatment. In addition, observational studies suggest that the risk of breast cancer was greater, and became apparent earlier, with estrogen/progestin combination therapy as compared to estrogen-alone therapy.
In the CE/MPA substudy, 26% of the women reported prior use of estrogen-alone and/or estrogen/progestin combination hormone therapy. After a mean follow-up of 5.6 years during the clinical trial, the relative risk of invasive breast cancer was 1.24 (95% nCI, 1.01-1.54), and the absolute risk was 41 versus 33 cases per 10,000 women-years, for CE/MPA compared with placebo. Among women who reported prior use of hormone therapy, the relative risk of invasive breast cancer was 1.86, and the absolute risk was 46 versus 25 cases per 10,000 women-years, for CE/MPA compared with placebo. Among women who reported no prior use of hormone therapy, the relative risk of invasive breast cancer was 1.09, and the absolute risk was 40 versus 36 cases per 10,000 women-years, for CE/MPA compared with placebo. In the same substudy, invasive breast cancers were larger and diagnosed at a more advanced stage in the CE/MPA group compared with the placebo group. Metastatic disease was rare with no apparent difference between the two groups. Other prognostic factors such as histologic subtype, grade and hormone receptor status did not differ between the groups.
The use of estrogen alone and estrogen plus progestin has been reported to result in an increase in abnormal mammograms requiring further evaluation. All women should receive yearly breast examinations by a healthcare provider and perform monthly self-examinations. In addition, mammography examinations should be scheduled based on patient age, risk
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