Estradiol

Limitation of Use

When prescribing solely for the treatment of moderate to severe symptoms of vulvar and vaginal atrophy, topical vaginal products should be considered.

Limitation of Use

When prescribing solely for the prevention of postmenopausal osteoporosis, therapy should only be considered for women at significant risk of osteoporosis and non-estrogen medications should be carefully considered.

Start therapy with estradiol transdermal system 0.0375 mg per day applied to the skin twice weekly. Dosage adjustment should be guided by the clinical response. In women not currently taking oral estrogens or in women switching from another estradiol transdermal therapy, treatment with estradiol transdermal system may be initiated at once. In women who are currently taking oral estrogens, treatment with estradiol transdermal system should be initiated 1 week after withdrawal of oral hormone therapy, or sooner if menopausal symptoms reappear in less than 1 week. Attempts to taper or discontinue the medication should be made at 3 to 6 month intervals.

Estradiol transdermal system may be given continuously in patients who do not have an intact uterus. In those patients with an intact uterus, estradiol transdermal system may be given on a cyclic schedule (for example, 3 weeks on drug followed by 1 week off drug).

Start therapy with estradiol transdermal system 0.0375 mg per day applied to the skin twice weekly. Dosage adjustment should be guided by the clinical response. Attempts to taper or discontinue the medication should be made at 3 to 6 month intervals.

In women not currently taking oral estrogens or in women switching from another estradiol transdermal therapy, treatment with estradiol transdermal system may be initiated at once. In women who are currently taking oral estrogens, treatment with estradiol transdermal system should be initiated 1 week after withdrawal of oral hormone therapy, or sooner if menopausal symptoms reappear in less than 1 week.

Estradiol transdermal system may be given continuously in patients who do not have an intact uterus. In those patients with an intact uterus, estradiol transdermal system may be given on a cyclic schedule (for example, 3 weeks on drug followed by 1 week off drug).

Start therapy with estradiol transdermal system 0.025 mg per day applied to the skin twice weekly.

In women not currently taking oral estrogen or in women switching from another estradiol transdermal therapy, treatment with estradiol transdermal system may be initiated at once. In women who are currently taking oral estrogens, treatment with estradiol transdermal system should be initiated 1 week after withdrawal of oral hormone therapy, or sooner if menopausal symptoms reappear in less than 1 week.

Estradiol transdermal system may be given continuously in patients who do not have an intact uterus. In those patients with an intact uterus, estradiol transdermal system may be given on a cyclic schedule (for example, 3 weeks on drug followed by 1 week off drug).

An increased risk of stroke and DVT has been reported with estrogen-alone therapy. An increased risk of PE, DVT, stroke, and MI has been reported with estrogen plus progestin therapy. Should any of these occur or be suspected, estrogen with or without progestin therapy should be discontinued immediately.

Risk factors for arterial vascular disease (for example, hypertension, diabetes mellitus, tobacco use, hypercholesterolemia, and obesity) and/or venous thromboembolism (VTE) (for example, personal history or family history of VTE, obesity, and systemic lupus erythematosus) should be managed appropriately.

Stroke

In the WHI estrogen-alone substudy, a statistically significant increased risk of stroke was reported in women 50 to 79 years of age receiving daily CE (0.625 mg)-alone compared to women in the same age group receiving placebo (45 versus 33 per 10,000 women-years). The increase in risk was demonstrated in year 1 and persisted [ see Clinical Studies ( 14.3 )]. Should a stroke occur or be suspected, estrogen-alone therapy should be discontinued immediately.

Subgroup analyses of women 50 to 59 of age suggest no increased risk of stroke for those women receiving CE (0.625 mg)-alone versus those receiving placebo (18 versus 21 per 10,000 women-years). ¹

In the WHI estrogen plus progestin substudy, a statistically significant increased risk of stroke was reported in women 50 to 79 years of age receiving CE (0.625 mg) plus MPA (2.5 mg) compared to women in the same age group receiving placebo (33 versus 25 per 10,000 women-years) [ see Clinical Studies ( 14.3)]. The increase in risk was demonstrated after the first year and persisted. Should a stroke occur or be suspected, estrogen plus progestin therapy should be discontinued immediately.

Coronary Heart Disease

In the WHI estrogen-alone substudy, no overall effect on coronary heart disease (CHD) events (defined as nonfatal MI, silent MI, or CHD death) was reported in women receiving estrogen-alone compared to placebo ² [see Clinical Studies ( 14.3 )].

Subgroup analyses of women 50 to 59 years of age suggest a statistically nonsignificant reduction in CHD events reported in women receiving daily CE (0.625 mg)-alone compared to placebo in women less than 10 years since menopause (8 versus 16 per 10,000 women-years). ¹

In the WHI estrogen plus progestin substudy, there was a statistically nonsignificant increased risk of CHD events reported in women receiving daily CE (0.625 mg) plus MPA (2.5 mg) compared to women receiving placebo (41 versus 34 per 10,000 women-years). ¹ An increase in relative risk was demonstrated in year 1, and a trend toward decreasing relative risk was reported in years 2 through 5 [see Clinical Studies ( 14.3) ].

In postmenopausal women with documented heart disease (n=2,763, average 66.7 years of age), in a controlled clinical trial of secondary prevention of cardiovascular disease (Heart and Estrogen/Progestin Replacement Study; HERS), treatment with daily CE (0.625 mg) plus MPA (2.5 mg) demonstrated no cardiovascular benefit. During an average follow-up of 4.1 years, treatment with CE plus MPA did not reduce the overall rate of CHD events in postmenopausal women with established CHD. There were more CHD events in the CE plus MPA-treated group than in the placebo group in year 1, but not during the subsequent years. Two thousand three hundred twenty-one (2,321) 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 plus MPA group and the placebo group in the HERS, the HERS II, and overall.

Venous Thromboembolism

In the WHI estrogen-alone substudy, the risk of VTE (DVT and PE) was increased for women receiving daily CE (0.625 mg)-alone 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 2 years ³ [see Clinical Studies ( 14.3) ]. Should a VTE occur or be suspected, estrogen-alone therapy should be discontinued immediately.

In the WHI estrogen plus progestin substudy, a statistically significant 2‑fold greater rate of VTE was reported in women receiving daily CE (0.625 mg) plus MPA (2.5 mg) 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 demonstrated during the first year and persisted ⁴ [see Clinical Studies ( 14.3) ]. Should a VTE occur or be suspected, estrogen plus progestin therapy should be discontinued immediately.

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.

Endometrial Cancer

An increased risk of endometrial cancer has been reported with the use of unopposed estrogen therapy in a woman with a uterus. 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 the use of estrogens for less than 1 year. The greatest risk appears to be associated with prolonged use, with increased risks of 15‑ to 24‑fold for 5 to 10 years or more, and this risk has been shown to persist for at least 8 to 15 years after estrogen therapy is discontinued.

Clinical surveillance of all women using estrogen-alone or estrogen plus progestin therapy is important. Adequate diagnostic measures, including directed or random endometrial sampling when indicated, should be undertaken to rule out malignancy in postmenopausal women with undiagnosed persistent or recurring abnormal genital 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.

Breast Cancer

The most important randomized clinical trial providing information about breast cancer in estrogen-alone users is the WHI substudy of daily CE (0.625 mg)-alone. In the WHI estrogen-alone substudy, after an average follow-up of 7.1 years, daily CE (0.625 mg)-alone was not associated with an increased risk of invasive breast cancer (relative risk [RR] 0.80) ⁵ [see Clinical Studies ( 14.3) ].

The most important randomized clinical trial providing information about breast cancer in estrogen plus progestin users is the WHI substudy of daily CE (0.625 mg) plus MPA (2.5 mg). After a mean follow-up of 5.6 years, the estrogen plus progestin substudy reported an increased risk of invasive breast cancer in women who took daily CE plus MPA.

In this substudy, prior use of estrogen-alone or estrogen plus progestin therapy was reported by 26 percent of the women. The relative risk of invasive breast cancer was 1.24, and the absolute risk was 41 versus 33 cases per 10,000 women-years, for CE plus 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 plus MPA compared with placebo. ⁶ 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 plus MPA compared with placebo. In the same substudy, invasive breast cancers were larger, were more likely to be node positive, and were diagnosed at a more advanced stage in the CE (0.625 mg) plus MPA (2.5 mg) group compared with the placebo group. Metastatic disease was rare, with no apparent difference between the 2 groups. Other prognostic factors, such as histologic subtype, grade, and hormone receptor status did not differ between the groups [see Clinical Studies ( 14.3 )].

Consistent with the WHI clinical trial, observational studies have also reported an increased risk of breast cancer for estrogen plus progestin therapy, and a smaller increased risk for estrogen-alone therapy, after several years of use. The risk increased with duration of use, and appeared to return to baseline over about 5 years after stopping treatment (only the observational studies have substantial data on risk after stopping). Observational studies also suggest that the risk of breast cancer was greater, and became apparent earlier, with estrogen plus progestin therapy as compared to estrogen-alone therapy. However, these studies have not found significant variation in the risk of breast cancer among different estrogen plus progestin combinations, doses, or routes of administration.

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 breast self‑examinations. In addition, mammography examinations should be scheduled based on patient age, risk factors, and prior mammogram results.

Ovarian Cancer

The WHI estrogen plus progestin substudy reported a statistically nonsignificant increased risk of ovarian cancer. After an average follow-up of 5.6 years, the relative risk for ovarian cancer for CE plus MPA versus placebo was 1.58 (95 percent CI, 0.77 to 3.24). The absolute risk for CE plus MPA versus placebo was 4 versus 3 cases per 10,000 women-years ^.7. In some epidemiologic studies, the use of estrogen plus progestin and estrogen-only products, in particular for 5 or more years, has been associated with an increased risk of ovarian cancer. However, the duration of exposure associated with increased risk is not consistent across all epidemiologic studies and some report no association.

In the WHIMS estrogen-alone ancillary study of WHI, a population of 2,947 hysterectomized women 65 to 79 years of age was randomized to daily CE (0.625 mg)-alone or placebo.

After an average follow-up of 5.2 years, 28 women in the estrogen-alone group and 19 women in the placebo group were diagnosed with probable dementia. The relative risk of probable dementia for CE-alone versus placebo was 1.49 (95 percent CI, 0.83 to 2.66). The absolute risk of probable dementia for CE-alone versus placebo was 37 versus 25 cases per 10,000 women-years ⁸ [see Use in Specific Populations ( 8.5), and Clinical Studies ( 14.4) ].

In the WHIMS estrogen plus progestin ancillary study of WHI, a population of 4,532 postmenopausal women 65 to 79 years was randomized to daily CE (0.625 mg) plus MPA (2.5 mg) or placebo.

After an average follow‑up of 4 years, 40 women in the CE plus MPA group and 21 women in the placebo group were diagnosed with probable dementia. The relative risk of probable dementia for CE plus MPA versus placebo was 2.05 (95 percent CI, 1.21 to 3.48). The absolute risk of probable dementia for CE plus MPA versus placebo was 45 versus 22 cases per 10,000 women‑years8 [see Use in Specific Populations ( 8.5), and Clinical Studies ( 14.4) ].

When data from the 2 populations in the WHIMS estrogen-alone and estrogen plus progestin ancillary studies were pooled as planned in the WHIMS protocol, the reported overall relative risk for probable dementia was 1.76 (95 percent CI, 1.19 to 2.60). Since both ancillary studies were conducted in women aged 65 to 79 years of age, it is unknown whether these findings apply to younger postmenopausal women ⁸ [see Use in Specific Populations ( 8.5), and Clinical Studies ( 14.4) ].

A 2‑ to 4‑fold increase in the risk of gallbladder disease requiring surgery in postmenopausal women receiving estrogens has been reported.

Estrogen administration may lead to severe hypercalcemia in women with breast cancer and bone metastases. If hypercalcemia occurs, use of the drug should be stopped and appropriate measures taken to reduce the serum calcium level.

Retinal vascular thrombosis has been reported in women 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 permanently discontinued.

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 lowered 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 an increased risk of breast cancer.

In a small number of case reports, substantial increases in blood pressure have been attributed to idiosyncratic reactions to estrogens. In a large, randomized, placebo‑controlled clinical trial, a generalized effect of estrogens on blood pressure was not seen.

In women with preexisting hypertriglyceridemia, estrogen therapy may be associated with elevations of plasma triglycerides leading to pancreatitis. Consider discontinuation of treatment if pancreatitis occurs.

Estrogens may be poorly metabolized in women with impaired liver function. For women 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.

Estrogen administration leads to increased thyroid‑binding globulin (TBG) levels. Women with normal thyroid function can compensate for the increased TBG by making more thyroid hormone, thus maintaining free T ₄ and T ₃ serum concentrations in the normal range. Women dependent on thyroid hormone replacement therapy who are also receiving estrogens may require increased doses of their thyroid replacement therapy. These women should have their thyroid function monitored in order to maintain their free thyroid hormone levels in an acceptable range.

Estrogens may cause some degree of fluid retention. Women with conditions that might be influenced by this factor, such as cardiac or renal impairment, warrant careful observation when estrogen-alone is prescribed.

Estrogen therapy should be used with caution in women with hypoparathyroidism as estrogen-induced hypocalcemia may occur.

A few cases of malignant transformation of residual endometrial implants have been reported in women treated post‑hysterectomy with estrogen-alone therapy. For women known to have residual endometriosis post‑hysterectomy, the addition of progestin should be considered.

Cases of anaphylactic/anaphylactoid reactions, which developed anytime during the course of estradiol transdermal system treatment and required emergency medical management, have been reported in the postmarketing setting. Involvement of skin (hives, pruritus, swollen lips-tongue-face) and either respiratory tract (respiratory compromise) or gastrointestinal tract (abdominal pain, vomiting) has been noted.

Angioedema involving eye/eyelid, face, larynx, pharynx, tongue and extremity (hands, legs, ankles, and fingers) with or without urticaria requiring medical intervention has occurred in the postmarketing experience of using estradiol transdermal system. If angioedema involves the tongue, glottis, or larynx, airway obstruction may occur. Patients who develop angioedema anytime during the course of treatment with estradiol transdermal system should not receive it again.

Exogenous estrogens may exacerbate symptoms of angioedema in women with hereditary angioedema.

Estrogen therapy may cause an exacerbation of asthma, diabetes mellitus, epilepsy, migraines, porphyria, systemic lupus erythematosus, and hepatic hemangiomas and should be used with caution in women with these conditions.

Serum follicle-stimulating hormone (FSH) and estradiol levels have not been shown to be useful in the management of moderate to severe vasomotor symptoms and moderate to severe symptoms of vulvar and vaginal atrophy.

Laboratory parameters may be useful in guiding dosage for the treatment of hypoestrogenism due to hypogonadism, castration and primary ovarian failure.

• 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 anti‑factor Xa and antithrombin III; decreased antithrombin III activity; increased levels of fibrinogen and fibrinogen activity; increased plasminogen antigen and activity.
• Increased thyroid-binding globulin (TBG) leading to increased circulating total thyroid hormone levels, as measured by protein‑bound iodine (PBI), T ₄ levels (by column or by radioimmunoassay) or T ₃ levels by radioimmunoassay. T3 resin uptake is decreased, reflecting the elevated TBG. Free T ₄ and free T ₃ concentrations are unaltered. Women on thyroid replacement therapy may require higher doses of thyroid hormone.
• Other binding proteins may be elevated in serum, for example, corticosteroid-binding globulin (CBG), sex hormone-binding globulin (SHBG), leading to increased total circulating corticosteroids and sex steroids, respectively. Free hormone concentrations, such as testosterone and estradiol, may be decreased. Other plasma proteins may be increased (angiotensinogen/renin substrate, alpha‑1‑antitrypsin, ceruloplasmin).
• Increased plasma high-density lipoprotein (HDL) and HDL ₂ cholesterol subfraction concentrations, reduced low-density lipoprotein (LDL) cholesterol concentration, increased triglycerides levels.
• Impaired glucose tolerance.

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. There were no clinical trials conducted with estradiol transdermal system. Estradiol transdermal system is bioequivalent to the original formulation of estradiol transdermal system. The following adverse reactions have been reported with the original estradiol formulation therapy:

Table 1. Summary of Most Frequently Reported Adverse Reactions Regardless of Relationship Reported at a Frequency ≥5 Percent

† Represents milligrams of estradiol delivered daily by each system

* NOS represents no otherwise specified

**NEC represents not elsewhere classified

***Application site erythema and application site irritation were observed in a small number of patients (3.2% or less of patients across treatment group

The following additional adverse reactions have been identified during post-approval use of estradiol transdermal system. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Genitourinary System

Vaginal hemorrhage and abnormal withdrawal bleeding or flow, breakthrough bleeding, spotting, uterine leiomyomata, vaginitis, vaginal discharge, ovarian cancer, endometrial hyperplasia, dysmenorrhea.

Breast

Enlargement, pain, nipple discharge, fibrocystic breast changes, breast cancer.

Cardiovascular

Deep venous thrombosis, pulmonary embolism, thrombophlebitis.

Gastrointestinal

Nausea, vomiting, abdominal cramps, bloating, cholelithiasis, liver function tests abnormal, diarrhea.

Skin

Application site reactions include localized bleeding, bruising, burning, discomfort, dryness, eczema, edema, erythema, erythema multiforme, erythema nodosum, inflammation, irritation, pain, papules and vesicles. Other skin reactions include paresthesia, skin discoloration, skin pigmentation, urticaria, swelling, loss of scalp hair, hirsutism, pruritus, rash.

Eyes

Intolerance to contact lenses.

Central Nervous System

Migraine, dizziness, chorea, nervousness, affect liability, irritability.

Miscellaneous

Decrease in weight, reduced carbohydrate tolerance, edema, arthralgias, leg cramps, changes in libido, purpura, hypersensitivity, anaphylactic reaction, anaphylactoid reaction, angioedema.

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 ( Hypericum perforatum) preparations, 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 may result in side effects.

Estradiol transdermal system should not be used during pregnancy [ see Contraindications ( 4) ]. There appears to be little or no increased risk of birth defects in children born to women who have used estrogens and progestins as an oral contraceptive inadvertently during early pregnancy.

Estradiol transdermal system should not be used during lactation. Estrogen administration to nursing women has been shown to decrease the quantity and quality of the breast milk. Detectable amounts of estrogens have been identified in the breast milk of women receiving estrogens. Caution should be exercised when estradiol transdermal system is administered to a nursing woman.

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.

Large and repeated doses of estrogen over an extended time period have been shown to accelerate epiphyseal closure, which could result in short adult stature if treatment is initiated before the completion of physiologic puberty in normally developing children. If estrogen is administered to patients whose bone growth is not complete, periodic monitoring of bone maturation and effects on epiphyseal centers is recommended during estrogen administration.

Estrogen treatment of prepubertal girls also induces premature breast development and vaginal cornification, and may induce vaginal bleeding.

There have not been sufficient numbers of geriatric women involved in clinical studies utilizing estradiol transdermal system to determine whether those over 65 years of age differ from younger subjects in their response to estradiol transdermal system.

The Women’s Health Initiative Studies

In the WHI estrogen-alone substudy (daily CE [0.625 mg]-alone versus placebo), there was a higher relative risk of stroke in women greater than 65 years of age [see Warnings and Precautions ( 5.1), and Clinical Studies ( 14.3) ].

In the WHI estrogen plus progestin substudy (daily CE [0.625 mg] plus MPA [2.5 mg] versus placebo), there was a higher relative risk of nonfatal stroke and invasive breast cancer in women greater than 65 years of age [see Warnings and Precautions ( 5.1), and Clinical Studies ( 14.3) ].

The Women’s Health Initiative Memory Study

In the WHIMS ancillary studies of postmenopausal women 65 to 79 years of age, there was an increased risk of developing probable dementia in women receiving estrogen-alone or estrogen plus progestin when compared to placebo [ see Warnings and Precautions ( 5.3), and Clinical Studies ( 14.4) ].

Since both ancillary studies were conducted in women 65 to 79 years of age, it is unknown whether these findings apply to younger postmenopausal women [ see Warnings and Precautions ( 5.3), and Clinical Studies ( 14.4) ]

The effect of renal impairment on the pharmacokinetics of estradiol transdermal system has not been studied.

The effect of hepatic impairment on the pharmacokinetics of estradiol transdermal system has not been studied.

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 in the 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, 2 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.

There are no pharmacodynamics data for estradiol transdermal system.

Absorption

In a multiple‑dose study consisting of 3 consecutive system applications of the original formulation of estradiol transdermal system which was conducted in 17 healthy, postmenopausal women, blood levels of estradiol and estrone were compared following application of these units to sites on the abdomen and buttocks in a crossover fashion. Systems that deliver nominal estradiol doses of approximately 0.0375 mg per day and 0.1 mg per day were applied to abdominal application sites while the 0.1 mg per day doses were also applied to sites on the buttocks. These systems increased estradiol levels above baseline within 4 hours and maintained respective mean levels of 25 and 79 pg/mL above baseline following application to the abdomen; slightly higher mean levels of 88 pg/mL above baseline were observed following application to the buttocks. At the same time, increases in estrone plasma concentrations averaged about 12 and 50 pg/mL, respectively, following application to the abdomen and 61 pg/mL for the buttocks. While plasma concentrations of estradiol and estrone remained slightly above baseline at 12 hours following removal of the systems in this study, results from another study show these levels to return to baseline values within 24 hours following removal of the systems.

Figure 1 illustrates the mean plasma concentrations of estradiol at steady‑state during application of these patches at 4 different dosages.

• Figure 1. Steady‑State Estradiol Plasma Concentrations for Systems Applied to the Abdomen Nonbaseline‑corrected Levels
• Figure 1 Steady-State Estradiol Plasma Concentrations for Systems Applied to the Abdomen

The corresponding pharmacokinetic parameters are summarized in Table 2.

Table 2. Steady-State Estradiol Pharmacokinetic Parameters for Systems Applied to the Abdomen (mean ± standard deviation) Nonbaseline-corrected Data*

*Mean baseline estradiol concentration = 11.7 pg/mL
†Peak plasma concentrations

‡ Average plasma concentration

§ Minimum plasma concentration at 84 hr

# Measured over 80 hr

^¶ Applied to the buttocks

Estradiol transdermal system, the revised formulation with smaller system sizes, was shown to be bioequivalent to the original formulation of the estradiol transdermal system used in the clinical trials.

Distribution

No specific investigation of the tissue distribution of estradiol absorbed from the estradiol transdermal system in humans has been conducted. 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 the blood largely bound to sex hormone-binding globulin (SHBG) and albumin.

Metabolism

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 by Cytochrome 450 isoforms CYP1A2 and CYP3A4. Estradiol undergoes further metabolism to sulfate and glucuronide conjugates. Estradiol and its metabolites are glucuronidated by UGT1A1 and UGT2B7. Estradiol is converted reversibly to estrone, and both can be converted to estriol, which is a 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 portion of the circulating estrogens exist as sulfate conjugates, especially estrone sulfate, which serves as a circulating reservoir for the formation of more active estrogens.

Excretion

Estradiol, estrone and estriol are excreted in the urine along with glucuronide and sulfate conjugates. The half-life values calculated after dosing with the estradiol transdermal system ranges from 5.9 to 7.7 hours. After removal of the transdermal systems, serum concentrations of estradiol and estrone returned to baseline levels within 24 hours.

Use in Specific Populations

No pharmacokinetic studies were conducted with estradiol transdermal system in specific populations, including women with renal or hepatic impairment.

Adhesion

Based on combined data from 3 short-term clinical trials consisting of 471 observations, 85 percent of estradiol transdermal systems adhered completely to the skin over the 3.5-day wear period. The (3) percent of the systems detached and were reapplied or replaced during the 3.5-day wear period. Approximately 80 percent of the transdermal systems evaluated in these studies were estradiol transdermal system 0.05 mg per day.

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.

In a pharmacokinetic study, estradiol transdermal system was shown to be bioequivalent to the original estradiol formulation. In 2 controlled clinical trials with the original estradiol formulation, of 356 subjects, the 0.075 and 0.1 mg doses were superior to placebo in relieving vasomotor symptoms at Week 4, and maintained efficacy through Weeks 8 and 12 of treatment. In this original study, the 0.0375 and 0.05 mg doses, however, did not differ from placebo until approximately Week 6, therefore, an additional 12-week, placebo‑controlled study in 255 patients was performed with the original estradiol formulation to establish the efficacy of the lowest dose of 0.0375 mg. The baseline mean daily number of hot flushes in these 255 patients was 11.5. Results at Weeks 4, 8, and 12 of treatment are shown in Figure 2.

Figure 2. Mean (SD) Change from Baseline in Mean Daily Number of Flushes for Estradiol 0.0375 mgVersusPlacebo in a 12 week Trail

The 0.0375 mg dose was superior to placebo in reducing both the frequency and severity of vasomotor symptoms at Week 4 and maintained efficacy through Weeks 8 and 12 of treatment. All doses of the original estradiol formulation (0.0375 mg, 0.05 mg, 0.075 mg, and 0.1 mg) are effective for the control of vasomotor symptoms.

Efficacy and safety of the original estradiol formulation in the prevention of postmenopausal osteoporosis have been studied in a 2‑year, double‑blind, randomized, placebo‑controlled, parallel group study. A total of 261 hysterectomized (161) and non‑hysterectomized (100), surgically or naturally menopausal women (within 5 years of menopause), with no evidence of osteoporosis (lumbar spine bone mineral density within 2 standard deviations of average peak bone mass, i.e., at least 0.827 g/cm ²) were enrolled in this study; 194 patients were randomized to 1 of the 4 doses of the original estradiol formulation (0.1, 0.05, 0.0375, or 0.025 mg/day) and 67 patients to placebo. Over 2 years, study systems were applied to the buttock or the abdomen twice a week. Non‑hysterectomized women received oral medroxyprogesterone acetate (2.5 mg/day) throughout the study.

The study population comprised naturally (82 percent) or surgically (18 percent) menopausal, hysterectomized (61 percent) or non‑hysterectomized (39 percent) women with a mean age of 52 years (range 27 to 62 years); the mean duration of menopause was 31.7 months (range 2 to 72 months). Two hundred thirty‑two (89 percent) of randomized subjects (173 on active drug, 59 on placebo) contributed data to the analysis of percent change from baseline in bone mineral density (BMD) of the AP lumbar spine, the primary efficacy variable. Patients were given supplemental dietary calcium (1,000 mg elemental calcium/day) but no supplemental vitamin D. There was an increase in BMD of the AP lumbar spine in all the original estradiol formulation dose groups; in contrast to this, a decrease in AP lumbar spine BMD was observed in placebo patients. All estradiol doses were significantly superior to placebo (p<0.05) at all time points with the exception of estradiol 0.05 mg/day at 6 months. The highest dose of estradiol was superior to the 3 lower doses. There were no statistically significant differences in pairwise comparisons among the 3 lower doses. (See Figure 3).

Figure 3. Bone Mineral Density‑AP Lumbar Spine Least Squares Means of Percentage Change from Baseline All Randomized Patients with at Least One Post‑baseline Assessment Available with Last Post‑baseline Observation Carried Forward

Analysis of percent change baseline in femoral neck BMD, a secondary efficacy outcome variable, showed qualitatively similar results; all doses of the original estradiol formulation were significantly superior to placebo (p<0.05) at 24 months. The highest estradiol dose was superior to placebo at all time points. A mixture of significant and nonsignificant results were obtained for the lower dose groups at earlier time points. The highest estradiol dose was superior to the 3 lower doses, and there were no significant differences among the 3 lower doses at this skeletal site. (See Figure 4).

Figure 4. Bone Mineral Density‑Femoral Neck Least Squares Means of Percentage Change from Baseline All Randomized Patients with at Least One Post‑baseline Assessment Available with Last Post‑baseline Observation Carried Forward.

The mean serum osteocalcin (a marker of bone formulation) and urinary excretion of cross-link N-telopeptides of Type I collagen (a marker of bone resorption) decreased numerically in most of the active treatment groups relative to baseline. However, the decreases in both markers were inconsistent across treatment groups and the differences between active treatment groups and placebo were not statistically significant.

The WHI enrolled approximately 27,000 predominantly healthy postmenopausal women in 2 substudies to assess the risks and benefits of daily oral CE (0.625 mg)-alone or in combination with the MPA (2.5 mg) compared to placebo in the prevention of certain chronic diseases. The primary endpoint was the incidence of CHD (defined as nonfatal MI, silent MI, and CHD death), with invasive breast cancer as the primary adverse outcome. A “global index” included the earliest occurrence of CHD, invasive breast cancer, stroke, PE, endometrial cancer (only in the CE plus MPA substudy), colorectal cancer, hip fracture, or death due to other causes. These substudies did not evaluate the effects of CE-alone or CE plus MPA on menopausal symptoms.

WHI Estrogen-Alone Substudy

The WHI estrogen-alone substudy was stopped early because an increased risk of stroke was observed, and it was deemed that no further information would be obtained regarding the risks and benefits of estrogen-alone in predetermined primary endpoints. Results of the estrogen-alone substudy, which included 10,739 women (average 63 years of age, range 50 to 79; 75.3 percent white, 15.1 percent black, 6.1 percent Hispanic, 3.6 percent Other) after an average follow-up of 7.1 years, are presented in Table 3.

Table 3. Relative and Absolute Risk Seen in the Estrogen-Alone Substudy of WHI ^a

^aAdapted from numerous WHI publications. WHI publications can be viewed at www.nhlbi.nih.gov/whi.

^b Nominal confidence intervals unadjusted for multiple looks and multiple comparisons.

^c Results are based on centrally adjudicated data for an average follow-up of 7.1 years.

^dNot included in “global index”.

^eResults are based on an average follow-up of 6.8 years.

^f All deaths, except from breast or colorectal cancer, definite or peobable CHD, PE or cerebrovascular disease.

^g All subset of the events was combined in a “global index”, defined as the earliest occurrence of CHD events, invasive breast cancer, stroke, pulmonary embolism, colorectal cancer, hip fracture, or death due to other causes.

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-alone was 12 more strokes, while the absolute risk reduction per 10,000 women-years was 7 fewer hip fractures. ⁹ The absolute excess risk of events included in the “global index” was a nonsignificant 5 events per 10,000 women-years. There was no difference between the groups in terms of all-cause mortality.

No overall difference for primary CHD events (nonfatal MI, silent MI and CHD death) and invasive breast cancer incidence in women receiving CE-alone compared with placebo was reported in final centrally adjudicated results from the estrogen-alone substudy, after an average follow-up of 7.1 years. (See Table 3)

Centrally adjudicated results for stroke events from the estrogen-alone substudy, after an average follow-up of 7.1 years, reported no significant differences in distribution of stroke subtype or severity, including fatal strokes, in women receiving CE-alone compared to placebo. Estrogen-alone increased the risk for ischemic stroke, and this excess risk was present in all subgroups of women examined. ¹⁰ (See Table 3).

Timing of the initiation of estrogen therapy relative to the start of menopause may affect the overall risk benefit profile. The WHI estrogen-alone substudy stratified by age showed in women 50 to 59 years of age a nonsignificant trend toward reduced risk for CHD [hazard ratio (HR) 0.63 (95 percent CI, 0.36 to 1.09)] and overall mortality [HR 0.71 (95 percent CI, 0.46 to 1.11)].

WHI Estrogen Plus Progestin Substudy

The WHI estrogen plus progestin substudy was stopped early. According to the predefined stopping rule, after an average follow-up of 5.6 years of treatment, the increased risk of invasive breast cancer and cardiovascular events exceeded the specified benefits included in the “global index”. The absolute excess risk of events included in the “global index” was 19 per 10,000 women-years.

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 plus MPA were 7 more CHD events, 8 more strokes, 10 more PEs, and 8 more invasive breast cancers, while the absolute risk reduction per 10,000 women-years were 6 fewer colorectal cancers and 5 fewer hip fractures.

Results of the estrogen plus progestin substudy, which included 16,608 women (average 63 years of age, range 50 to 79, 83.9 percent white, 6.8 percent black, 5.4 percent Hispanic, 3.9 percent Other) are presented in Table 4. These results reflect centrally adjudicated data after an average follow-up of 5.6 years.

Table 4. Relative and Absolute Risk Seen in the Estrogen Plus Progestin Substudy of WHI at an Average of 5.6 Years ^{a ,b}

^aAdapted from numerous WHI publications. WHI publications can be viewed at www.nhlbi.nih.gov/whi.
^bResults are based on centrally adjudicated data.
^cNominal confidence intervals unadjusted for multiple looks and multiple comparisons.
^dNot included in “global index”.
^eIncludes metastic and non-metastic breast cancer, with the exception of in situ breast cancer.
^fAll deaths, except from breast or colorectral cancer, definite or probably CHD, PE or cerebrovascular disease.
^gA subset of the events was combined in a “global index”, defined as the earliest occurrence of CHD events, invasive breast cancer, stroke, pulmonary embolism, colorectal cancer, hip fracture, or death due to other causes.

Timing of the initiation of estrogen plus progestin therapy relative to the start of menopause may affect the overall risk benefit profile. The WHI estrogen plus progestin substudy stratified by age showed in women 50 to 59 years of age a nonsignificant trend toward reduced risk for overall mortality [HR 0.69 (95 percent CI, 0.44 to 1.07)].

The WHIMS estrogen-alone ancillary study of WHI enrolled 2,947 predominantly healthy hysterectomized postmenopausal women 65 to 79 years of age (45 percent were age 65 to 69 years of age; 36 percent were 70 to 74 years of age; 19 percent were 75 years of age and older) to evaluate the effects of daily CE (0.625 mg)-alone on the incidence of probable dementia (primary outcome) compared to placebo.

After an average follow-up of 5.2 years, the relative risk of probable dementia for CE-alone versus placebo was 1.49 (95 percent CI, 0.83 to 2.66). The absolute risk of probable dementia for CE-alone versus placebo was 37 versus 25 cases per 10,000 women-years. Probable dementia as defined in this study included Alzheimer’s disease (AD), vascular dementia (VaD), and mixed types (having features of both AD and VaD). The most common classification of probable dementia in the treatment group and the placebo group was AD. Since the ancillary study was conducted in women 65 to 79 years of age, it is unknown whether these findings apply to younger postmenopausal women [see Warnings and Precautions ( 5.3) and Use in Specific Populations ( 8.5) ].

The WHIMS estrogen plus progestin ancillary study enrolled 4,532 predominantly healthy postmenopausal women 65 years of age and older (47 percent were age 65 to 69 years of age; 35 percent were 70 to 74 years of age; 18 percent were 75 years of age and older) to evaluate the effects of daily CE (0.625 mg) plus MPA (2.5 mg) on the incidence of probable dementia (primary outcome) compared to placebo.

After an average follow‑up of 4 years, the relative risk of probable dementia for CE plus MPA was 2.05 (95 percent CI, 1.21 to 3.48). The absolute risk of probable dementia for CE plus MPA versus placebo was 45 versus 22 per 10,000 women-years. Probable dementia as defined in this study included AD, VaD, and mixed type (having features of both AD and VaD). The most common classification of probable dementia in the treatment group and the placebo group was AD. Since the ancillary study was conducted in women 65 to 79 years of age, it is unknown whether these findings apply to younger postmenopausal women [see Warnings and Precautions ( 5.3) and Use in Specific Populations ( 8.5) ].

When data from the 2 populations were pooled as planned in the WHIMS protocol, the reported overall relative risk for probable dementia was 1.76 (95 percent CI, 1.19 to 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 Warnings and Precautions ( 5.3) and Use in Specific Populations ( 8.5)].

Estradiol Transdermal System

(ess-trah-DYE-ole)

1. Determine Your Schedule for Your Twice-a-Week Application

2. Where to Apply Estradiol Transdermal System

Where to apply Estradiol Transdermal System

Apply patch to a dry area of the skin of the trunk of the body, including the lower abdomen, or buttocks. Avoid the waistline, since clothing may cause the patch to rub off. Do not apply patch to breasts. When changing your patch, based on your twice-a-week schedule, apply your new patch to a different site. Do not apply a new patch to that same area for at least 1 week.

3. Before You Apply Estradiol Transdermal System

4. How to Apply Estradiol Transdermal System

Note:

• Showering will not cause your patch to fall off.
• If your patch falls off reapply it. If you cannot reapply the patch, apply a new patch to another area and continue to follow your original placement schedule.
• If you stop using your estradiol transdermal system patch or forget to apply a new patch as scheduled, you may have spotting, or bleeding, and recurrence of symptoms.
• 5. Throwing Away Your Used Patch
• When it is time to change your patch, remove the old patch before you apply a new patch.
• To throw away the patch, fold the sticky side of the patch together, place it in a sturdy child-proof container, and place the container in the trash. Used patches should not be flushed in the toilet.

This Patient Information and Instructions for Use have been approved by the U.S. Food and Drug Administration.

Manufactured by:

Noven Pharmaceuticals Inc.

Miami, FL 33186 for

Sandoz Inc.
Princeton, NJ 08540

T2014-81/T2014-82/T2014-83
July 2014/July 2014/July 2014