DESCRIPTION

Premarin ^® (conjugated estrogens tablets, USP) for oral administration contains a mixture of conjugated estrogens obtained exclusively from natural sources, occurring as the sodium salts of water-soluble estrogen sulfates blended to represent the average composition of material derived from pregnant mares' urine. It is a mixture of sodium estrone sulfate and sodium equilin sulfate. It contains as concomitant components, as sodium sulfate conjugates, 17(alpha)-dihydroequilin, 17(alpha)-estradiol, and 17(beta)-dihydroequilin. Tablets for oral administration are available in 0.3 mg, 0.45 mg, 0.625 mg, 0.9 mg, and 1.25 mg strengths of conjugated estrogens.

Premarin 0.3 mg, 0.45 mg, 0.625 mg, and 0.9 mg tablets contain the following inactive ingredients: calcium phosphate tribasic, calcium sulfate, carnauba wax, microcrystalline cellulose, powdered cellulose, glyceryl monooleate, lactose monohydrate, magnesium stearate, methylcellulose, pharmaceutical glaze, polyethylene glycol, stearic acid (not present in 0.45 mg tablet), sucrose, and titanium dioxide.

Premarin 1.25 mg tablets contain the following inactive ingredients: calcium phosphate tribasic, hydroxypropyl cellulose, microcrystalline cellulose, powdered cellulose, hypromellose, lactose monohydrate, magnesium stearate, polyethylene glycol, sucrose, and titanium dioxide.

• 0.3 mg tablets also contain: D&C Yellow No. 10, FD&C Blue No. 1, FD&C Blue No. 2, FD&C Yellow No. 6.
• 0.45 mg tablets also contain: FD&C Blue No. 2.
• 0.625 mg tablets also contain: FD&C Blue No. 2, D&C Red No. 27, FD&C Red No. 40.
• 0.9 mg tablets also contain: D&C Red No. 6, D&C Red No. 7.
• 1.25 mg tablets also contain: black iron oxide, D&C Yellow No. 10, FD&C Yellow No. 6.

Premarin tablets comply with USP Drug Release Test criteria as outlined below:

CLINICAL PHARMACOLOGY

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 gonadotropins seen in postmenopausal women.

Pharmacokinetics

Absorption

Conjugated estrogens are soluble in water and are well absorbed from the gastrointestinal tract after release from the drug formulation. The Premarin tablet releases conjugated estrogens slowly over several hours. Table 1 summarizes the mean pharmacokinetic parameters for unconjugated and conjugated estrogens following administration of 2 × 0.3 mg, 2 × 0.45 mg, and 2 × 0.625 mg tablets to healthy postmenopausal women.

Distribution

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 concentration 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. 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 gut followed by reabsorption. In postmenopausal women a significant proportion of the circulating estrogens exists 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.

Special Populations

No pharmacokinetic studies were conducted in special populations, including patients with renal or hepatic impairment.

Drug Interactions

Data from a single-dose drug-drug interaction study involving conjugated estrogens and medroxyprogesterone acetate indicate that the pharmacokinetic dispositions of both drugs are not altered when the drugs are coadministered. No other clinical drug-drug interaction studies have been conducted with conjugated estrogens.

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 may result in side effects.

Clinical Studies

Effects on vasomotor symptoms.

In the first year of the Health and Osteoporosis, Progestin and Estrogen (HOPE) Study, a total of 2805 postmenopausal women (average age 53.3 ± 4.9 years) were randomly assigned to one of eight treatment groups, receiving either placebo or conjugated estrogens with or without medroxyprogesterone acetate. Efficacy for vasomotor symptoms was assessed during the first 12 weeks of treatment in a subset of symptomatic women (n = 241) who had at least 7 moderate to severe hot flushes daily or at least 50 moderate to severe hot flushes during the week before randomization. Premarin (0.3 mg, 0.45 mg, and 0.625 mg tablets) was shown to be statistically better than placebo at weeks 4 and 12 for relief of both the frequency and severity of moderate to severe vasomotor symptoms. Table 2 shows the adjusted mean number of hot flushes in the Premarin 0.3 mg, 0.45 mg, and 0.625 mg and placebo treatment groups over the initial 12-week period.

Effects on vulvar and vaginal atrophy.

Results of vaginal maturation indexes at cycles 6 and 13 showed that the differences from placebo were statistically significant (p<0.001) for all treatment groups (conjugated estrogens alone and conjugated estrogens/medroxyprogesterone acetate treatment groups).

Effects on bone mineral density.
Health and Osteoporosis, Progestin and Estrogen (HOPE) Study

The HOPE study was a double-blind, randomized, placebo/active-drug-controlled, multicenter study of healthy postmenopausal women with an intact uterus. Subjects (mean age 53.3 ± 4.9 years) were 2.3 ± 0.9 years, on average, since menopause, and took one 600-mg tablet of elemental calcium (Caltrate) daily. Subjects were not given vitamin D supplements. They were treated with Premarin 0.625 mg, 0.45 mg, 0.3 mg, or placebo. Prevention of bone loss was assessed by measurement of bone mineral density (BMD), primarily at the anteroposterior lumbar spine (L ₂ to L ₄ ). Secondarily, BMD measurements of the total body, femoral neck, and trochanter were also analyzed. Serum osteocalcin, urinary calcium, and N-telopeptide were used as bone turnover markers (BTM) at cycles 6, 13, 19, and 26.

Intent-to-treat subjects

All active treatment groups showed significant differences from placebo in each of the 4 BMD endpoints at cycles 6, 13, 19, and 26. The mean percent increases in the primary efficacy measure (L ₂ to L ₄ BMD) at the final on-therapy evaluation (cycle 26 for those who completed and the last available evaluation for those who discontinued early) were 2.46% with 0.625 mg, 2.26% with 0.45 mg, and 1.13% with 0.3 mg. The placebo group showed a mean percent decrease from baseline at the final evaluation of 2.45%. These results show that the lower dosages of Premarin were effective in increasing L ₂ to L ₄ BMD compared with placebo and, therefore, support the efficacy of the lower doses.

The analysis for the other 3 BMD endpoints yielded mean percent changes from baseline in femoral trochanter that were generally larger than those seen for L ₂ to L ₄ and changes in femoral neck and total body that were generally smaller than those seen for L ₂ to L ₄ . Significant differences between groups indicated that each of the Premarin treatments was more effective than placebo for all 3 of these additional BMD endpoints. With regard to femoral neck and total body, the active treatment groups all showed mean percent increases in BMD while placebo treatment was accompanied by mean percent decreases. For femoral trochanter, each of the Premarin dose groups showed a mean percent increase that was significantly greater than the small increase seen in the placebo group. The percent changes from baseline to final evaluation are shown in Table 3.

The mean percent changes from baseline in L ₂ to L ₄ BMD for women who completed the bone density study are shown with standard error bars by treatment group in Figure 2. Significant differences between each of the Premarin dosage groups and placebo were found at cycles 6, 13, 19, and 26.

The bone turnover markers serum osteocalcin and urinary N-telopeptide significantly decreased (p<0.001) in all active-treatment groups at cycles 6, 13, 19, and 26 compared with the placebo group. Larger mean decreases from baseline were seen with the active groups than with the placebo group. Significant differences from placebo were seen less frequently in urine calcium.

Women's Health Initiative Studies.

The Women's Health Initiative (WHI) enrolled a total of 27,000 predominantly healthy postmenopausal women to assess the risks and benefits of either the use of Premarin (0.625 mg conjugated estrogens per day) alone or the use of PREMPRO™ (0.625 mg conjugated estrogens plus 2.5 mg medroxyprogesterone acetate 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 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, colorectal cancer, hip fracture, or death due to other cause. The study did not evaluate the effects of Premarin or PREMPRO on menopausal symptoms.

The 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 age of 63 years, range 50 to 79; 75.3% White, 15% Black, 6.1% Hispanic), after an average follow-up of 6.8 years are presented in Table 4 below.

The estrogen plus progestin substudy was also stopped early because, according to the predefined stopping rule, the increased risk of breast cancer and cardiovascular events exceeded the specified benefits included in the "global index." Results of the estrogen plus progestin substudy, which included 16,608 women (average age of 63 years, range 50 to 79; 83.9% White, 6.5% Black, 5.5% Hispanic), after an average follow-up of 5.2 years are presented in Table 5 below.

For those outcomes included in the WHI "global index," the absolute excess risks per 10,000 women-years in the group treated with PREMPRO were 7 more CHD events, 8 more strokes, 8 more PEs, and 8 more invasive breast cancers, while the absolute risk reductions per 10,000 women-years were 6 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. There was no difference between the groups in terms of all-cause mortality. (See BOXED WARNINGS , WARNINGS , and PRECAUTIONS .)

Women's Health Initiative Memory Study.

The estrogen alone Women's Health Initiative Memory Study (WHIMS), a substudy of WHI, enrolled 2,947 predominantly healthy postmenopausal women 65 years of age and older (45% were age 65 to 69 years, 36% were 70 to 74 years, and 19% were 75 years of age and older) to evaluate the effects of Premarin (0.625 mg conjugated estrogens) on the incidence of probable dementia (primary outcome) compared with placebo.

After an average follow-up of 5.2 years, 28 women in the estrogen 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 estrogen alone group was 1.49 (95% CI, 0.83 to 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 estrogen plus progestin 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 PREMPRO (0.625 mg conjugated estrogens plus 2.5 mg medroxyprogesterone acetate) on the incidence of probable dementia (primary outcome) compared with placebo.

After an average follow-up of 4 years, 40 women in the estrogen/progestin 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 to 3.48) compared to placebo. Differences between groups became apparent in the first year of treatment. It is unknown whether these findings apply to younger postmenopausal women. (See BOXED WARNINGS , WARNINGS , Dementia and PRECAUTIONS , Geriatric Use .)

INDICATIONS AND USAGE

Premarin therapy is indicated in the:

1. Treatment of moderate to severe vasomotor symptoms associated with the menopause.
2. Treatment of moderate to severe symptoms of vulvar and vaginal atrophy associated with the menopause. When prescribing solely for the treatment of symptoms of vulvar and vaginal atrophy, topical vaginal products should be considered.
3. Treatment of hypoestrogenism due to hypogonadism, castration or primary ovarian failure.
4. Treatment of breast cancer (for palliation only) in appropriately selected women and men with metastatic disease.
5. Treatment of advanced androgen-dependent carcinoma of the prostate (for palliation only).
6. Prevention of postmenopausal osteoporosis. When prescribing solely for the prevention of postmenopausal osteoporosis, therapy should only be considered for women at significant risk of osteoporosis and for whom non-estrogen medications are not considered to be appropriate. (See CLINICAL PHARMACOLOGY , Clinical Studies .)
   The mainstays for decreasing the risk of postmenopausal osteoporosis are weight-bearing exercise, adequate calcium and vitamin D intake, and when indicated, pharmacologic therapy. Postmenopausal women require an average of 1500 mg/day of elemental calcium. Therefore, when not contraindicated, calcium supplementation may be helpful for women with suboptimal dietary intake. Vitamin D supplementation of 400-800 IU/day may also be required to ensure adequate daily intake in postmenopausal women.

CONTRAINDICATIONS

Estrogens should not be used in individuals with any of the following conditions:

1. Undiagnosed abnormal genital bleeding.
2. Known, suspected, or history of cancer of the breast except in appropriately selected patients being treated for metastatic disease.
3. Known or suspected estrogen-dependent neoplasia.
4. Active deep vein thrombosis, pulmonary embolism or a history of these conditions.
5. Active or recent (e.g., within past year) arterial thromboembolic disease (e.g., stroke, myocardial infarction).
6. Liver dysfunction or disease.
7. Premarin tablets should not be used in patients with known hypersensitivity to their ingredients.
8. Known or suspected pregnancy. There is no indication for Premarin in pregnancy. There appears to be little or no increased risk of birth defects in children born to women who have used estrogen and progestins from oral contraceptives inadvertently during pregnancy. (See PRECAUTIONS .)

WARNINGS

See BOXED WARNINGS .

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.

1. Coronary heart disease and stroke. In the estrogen alone substudy of the Women's Health Initiative (WHI) study, an increased risk of stroke was observed in women receiving Premarin (0.625 mg conjugated estrogens) per day compared to women receiving placebo (44 vs 32 per 10,000 women-years). The increase in risk was observed in year one and persisted. (See CLINICAL PHARMACOLOGY , Clinical Studies .)
   In the estrogen plus progestin substudy of WHI, an increased risk of coronary heart disease (CHD) events (defined as nonfatal myocardial infarction and CHD death) was observed in women receiving PREMPRO (0.625 mg conjugated estrogens plus 2.5 mg medroxyprogesterone acetate) per day compared to women receiving placebo (37 vs 30 per 10,000 women-years). The increase in risk was observed in year one and persisted.
   In the same estrogen plus progestin substudy of WHI, an increased risk of stroke was observed in women receiving PREMPRO compared to women receiving placebo (29 vs 21 per 10,000 women-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 PREMPRO (0.625 mg conjugated estrogen plus 2.5 mg medroxyprogesterone acetate per day) demonstrated no cardiovascular benefit. During an average follow-up of 4.1 years, treatment with PREMPRO did not reduce the overall rate of CHD events in postmenopausal women with established coronary heart disease. There were more CHD events in the PREMPRO-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 PREMPRO 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 risk of nonfatal myocardial infarction, pulmonary embolism, and thrombophlebitis.
2. Venous thromboembolism (VTE). In the estrogen alone substudy of the Women's Health Initiative (WHI) study, an increased risk of deep vein thrombosis was observed in women receiving Premarin compared to placebo (21 vs 15 per 10,000 women-years). The increase in VTE risk was observed during the first year. (See CLINICAL PHARMACOLOGY , Clinical Studies .)
   In the estrogen plus progestin substudy of WHI, a 2-fold greater rate of VTE, including deep venous thrombosis and pulmonary embolism, was observed in women receiving PREMPRO compared to women receiving placebo. The rate of VTE was 34 per 10,000 women-years in the PREMPRO group compared to 16 per 10,000 women-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 the 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 with an intact uterus is about 2- to 12-fold 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 one year. The greatest risk appears associated with prolonged use, with increased risks of 15- to 24-fold for five to ten 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 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. In some studies, 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) trial of estrogen plus progestin (see CLINICAL PHARMACOLOGY , Clinical Studies ). The results from observational studies are generally consistent with those of the WHI clinical trial.

After a mean follow-up of 5.6 years, the WHI trial reported an increased risk of breast cancer in women who took estrogen plus progestin. 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. For both findings, the excess risk increased with duration of use, and appeared to return to baseline over about five years after stopping treatment (only the observational studies have substantial data on risk after stopping). In these studies, the risk of breast cancer was greater, and became apparent earlier, with estrogen/progestin combination therapy as compared to estrogen alone therapy. However, these studies have not found significant variation in the risk of breast cancer among different estrogens or among different estrogen/progestin combinations, doses, or routes of administration.

In the WHI trial of estrogen plus progestin, 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 overall relative risk of invasive breast cancer was 1.24 (95% confidence interval 1.01-1.54), and the overall absolute risk was 41 vs. 33 cases per 10,000 women-years, for estrogen plus progestin 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 vs. 25 cases per 10,000 women-years, for estrogen plus progestin 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 vs. 36 cases per 10,000 women-years for estrogen plus progestin compared with placebo. In the WHI trial, invasive breast cancers were larger and diagnosed at a more advanced stage in the estrogen plus progestin 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 observational Million Women Study in Europe reported an increased risk of mortality due to breast cancer among current users of estrogens alone or estrogens plus progestins compared to never users, while the estrogen plus progestin sub-study of WHI showed no effect on breast cancer mortality with a mean follow-up of 5.6 years.

The use of 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.

3. Dementia. In the estrogen alone Women's Health Initiative Memory Study (WHIMS), a substudy of WHI, a population of 2,947 hysterectomized women aged 65 to 79 years was randomized to Premarin (0.625 mg) or placebo. In the estrogen plus progestin WHIMS substudy, a population of 4,532 postmenopausal women aged 65 to 79 years was randomized to PREMPRO (0.625 mg/2.5 mg) or placebo.

In the estrogen alone substudy, 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 Premarin alone versus placebo was 1.49 (95% CI 0.83-2.66). The absolute risk of probable dementia for Premarin alone versus placebo was 37 versus 25 cases per 10,000 women-years.

In the estrogen plus progestin substudy, after an average follow-up of 4 years, 40 women in the estrogen plus progestin group and 21 women in the placebo group were diagnosed with probable dementia. The relative risk of probable dementia for estrogen plus progestin versus placebo was 2.05 (95% CI 1.21-3.48). The absolute risk of probable dementia for PREMPRO versus placebo was 45 versus 22 cases per 10,000 women-years.

Since both substudies were conducted in women aged 65 to 79 years, it is unknown whether these findings apply to younger postmenopausal women. (See BOXED WARNINGS and PRECAUTIONS , Geriatric Use .)

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

5. Hypercalcemia. Estrogen administration may lead to severe hypercalcemia in patients 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.

6. 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.

PRECAUTIONS

A. General

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 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: a possible increased risk of breast cancer, adverse effects on lipoprotein metabolism (e.g., lowering HDL, raising LDL) and impairment of glucose tolerance.
2. Elevated blood pressure.
   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 estrogen therapy on blood pressure was not seen. Blood pressure should be monitored at regular intervals during estrogen use.
3. Hypertriglyceridemia.
   In patients with pre-existing hypertriglyceridemia, estrogen therapy may be associated with elevations of plasma triglycerides leading to pancreatitis and other complications. In the HOPE study, the mean percent increase from baseline in serum triglycerides after one year of treatment with Premarin 0.625 mg, 0.45 mg, and 0.3 mg compared with placebo were 34.3, 30.2, 25.1, and 10.7, respectively. After two years of treatment, the mean percent changes were 47.6, 32.5, 19.0, and 5.5, respectively.
4. Impaired liver function and past history of cholestatic jaundice.
   Estrogens may be poorly metabolized in patients with impaired liver function. For patients 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 T ₄ and T ₃ 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, patients with conditions that might be influenced by this factor, such as 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.
   The estrogen plus progestin substudy of WHI reported that after an average follow-up of 5.6 years, the relative risk for ovarian cancer for estrogen plus progestin versus placebo was 1.58 (95% confidence interval 0.77 - 3.24) but was not statistically significant. The absolute risk of estrogen plus progestin versus placebo was 4.2 versus 2.7 cases per 10,000 women-years. In some epidemiologic studies, the use of estrogen-only products, in particular for ten or more years, has been associated with an increased risk of ovarian cancer. Other epidemiologic studies have not found these associations.
9. Exacerbation of endometriosis.
   Endometriosis may be exacerbated with administration of estrogen therapy.
   A few cases of malignant transformation of residual endometrial implants have been reported in women treated post-hysterectomy with estrogen alone therapy. For patients known to have residual endometriosis post-hysterectomy, the addition of progestin should be considered.
10. Exacerbation of other conditions.
    Estrogen therapy 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.

B. Patient Information

Physicians are advised to discuss the contents of the PATIENT INFORMATION leaflet with patients for whom they prescribe Premarin.

C. Laboratory Tests

Estrogen administration should be initiated at the lowest dose for the treatment of postmenopausal moderate to severe vasomotor symptoms and moderate to severe symptoms of postmenopausal vulvar and vaginal atrophy and then guided by clinical response rather than by serum hormone levels (e.g., estradiol, FSH). Laboratory parameters may be useful in guiding dosage for the treatment of hypoestrogenism due to hypogonadism, castration and primary ovarian failure.

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 anti-factor 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 levels as measured by protein-bound iodine (PBI), T ₄ levels (by column or by radioimmunoassay) or T ₃ levels by radioimmunoassay. T ₃ resin uptake is decreased, reflecting the elevated TBG. Free T ₄ and free T ₃ 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 (CBG), sex hormone binding globulin (SHBG), leading to increased total circulating corticosteroids and sex steroids, respectively. Free hormone concentrations may be decreased. 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 concentrations, increased triglyceride levels.
5. Impaired glucose tolerance.
6. Reduced response to metyrapone test.

E. Carcinogenesis, Mutagenesis, Impairment of Fertility

(See BOXED WARNINGS , WARNINGS , and PRECAUTIONS .)

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.

F. Pregnancy

Premarin 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 Premarin 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.

Large and repeated doses of estrogen over an extended time period have been shown to accelerate epiphyseal closure, which could result in short 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. In boys, estrogen treatment may modify the normal pubertal process and induce gynecomastia. See INDICATIONS and DOSAGE AND ADMINISTRATION sections.

I. Geriatric Use

Of the total number of subjects in the estrogen alone substudy of the Women's Health Initiative (WHI) study, 46% (n=4,943) were 65 years and over, while 7.1% (n=767) were 75 years and over. There was a higher relative risk (Premarin vs. placebo) of stroke in women less than 75 years of age compared to women 75 years and over.

In the estrogen alone substudy of the Women's Health Initiative Memory Study (WHIMS), a substudy of WHI, a population of 2,947 hysterectomized women, aged 65 to 79 years, was randomized to Premarin (0.625 mg) or placebo. In the estrogen alone group, after an average follow-up of 5.2 years, the relative risk (Premarin versus placebo) of probable dementia was 1.49 (95% CI 0.83-2.66).

Of the total number of subjects in the estrogen plus progestin substudy of the Women's Health Initiative study, 44% (n=7,320) were 65 years and over, while 6.6% (n=1,095) were 75 years and over. There was a higher relative risk (PREMPRO vs placebo) of stroke and invasive breast cancer in women 75 and over compared to women less than 75 years of age.

In the estrogen plus progestin substudy of WHIMS, a population of 4,532 postmenopausal women, aged 65 to 79 years, was randomized to PREMPRO (0.625 mg/2.5 mg) or placebo. In the estrogen plus progestin group, after an average follow-up of 4 years, the relative risk (PREMPRO versus placebo) of probable dementia was 2.05 (95% CI 1.21-3.48).

Pooling the events in women receiving Premarin or PREMPRO in comparison to those in women on placebo, the overall relative risk for probable dementia was 1.76 (95% CI 1.19-2.60). Since both substudies were conducted in women aged 65 to 79 years, it is unknown whether these findings apply to younger postmenopausal women. (See BOXED WARNINGS and WARNINGS , Dementia .)

With respect to efficacy in the approved indications, there have not been sufficient numbers of geriatric patients involved in studies utilizing Premarin to determine whether those over 65 years of age differ from younger subjects in their response to Premarin.

ADVERSE REACTIONS

See BOXED WARNINGS , WARNINGS , and PRECAUTIONS .

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. The adverse reaction information from clinical trials does, however, provide a basis for identifying the adverse events that appear to be related to drug use and for approximating rates.

During the first year of a 2-year clinical trial with 2333 postmenopausal women between 40 and 65 years of age (88% Caucasian), 1012 women were treated with conjugated estrogens and 332 were treated with placebo. Table 6 summarizes adverse events that occurred at a rate of >/= 5%.

1. Genitourinary system
   Changes in vaginal bleeding pattern and abnormal withdrawal bleeding or flow; breakthrough bleeding, spotting, dysmenorrhea
   Increase in size of uterine leiomyomata
   Vaginitis, including vaginal candidiasis
   Change in amount of cervical secretion
   Change in cervical ectropion
   Ovarian cancer
   Endometrial hyperplasia
   Endometrial cancer
2. Breasts
   Tenderness, enlargement, pain, discharge, galactorrhea
   Fibrocystic breast changes
   Breast cancer
3. Cardiovascular
   Deep and superficial venous thrombosis
   Pulmonary embolism
   Thrombophlebitis
   Myocardial infarction
   Stroke
   Increase in blood pressure
4. Gastrointestinal
   Nausea, vomiting
   Abdominal cramps, bloating
   Cholestatic jaundice
   Increased incidence of gallbladder disease
   Pancreatitis
   Enlargement of hepatic hemangiomas
5. Skin
   Chloasma or melasma that may persist when drug is discontinued
   Erythema multiforme
   Erythema nodosum
   Hemorrhagic eruption
   Loss of scalp hair
   Hirsutism
   Pruritus, rash
6. Eyes
   Retinal vascular thrombosis
   Intolerance to contact lenses
7. Central Nervous System
   Headache
   Migraine
   Dizziness
   Mental depression
   Chorea
   Nervousness
   Mood disturbances
   Irritability
   Exacerbation of epilepsy
   Dementia
8. Miscellaneous
   Increase or decrease in weight
   Reduced carbohydrate tolerance
   Aggravation of porphyria
   Edema
   Arthralgias
   Leg cramps
   Changes in libido
   Urticaria, angioedema, anaphylactoid/anaphylactic reactions
   Hypocalcemia
   Exacerbation of asthma
   Increased triglycerides

OVERDOSAGE

Serious ill effects have not been reported following acute ingestion of large doses of estrogen-containing drug products by young children. Overdosage of estrogen may cause nausea and vomiting, and withdrawal bleeding may occur in females.

DOSAGE AND ADMINISTRATION

When estrogen is prescribed for a postmenopausal woman with a uterus, progestin should also be initiated to reduce the risk of endometrial cancer. A woman without a uterus does not need progestin. Use of estrogen, alone or in combination with a progestin, should be with the lowest effective dose and for the shortest duration consistent with treatment goals and risks for the individual woman. Patients should be re-evaluated periodically as clinically appropriate (e.g., at 3-month to 6-month intervals) to determine if treatment is still necessary (see BOXED WARNINGS and WARNINGS ). For women with a uterus, adequate diagnostic measures, such as endometrial sampling, when indicated, should be undertaken to rule out malignancy in cases of undiagnosed persistent or recurring abnormal vaginal bleeding.

1. For treatment of moderate to severe vasomotor symptoms and/or moderate to severe symptoms of vulvar and vaginal atrophy associated with the menopause. When prescribing solely for the treatment of moderate to severe symptoms of vulvar and vaginal atrophy, topical vaginal products should be considered.
   Patients should be treated with the lowest effective dose. Generally women should be started at 0.3 mg Premarin daily. Subsequent dosage adjustment may be made based upon the individual patient response. This dose should be periodically reassessed by the healthcare provider.
   Premarin therapy may be given continuously with no interruption in therapy, or in cyclical regimens (regimens such as 25 days on drug followed by five days off drug) as is medically appropriate on an individualized basis.
2. For prevention of postmenopausal osteoporosis:
   When prescribing solely for the prevention of postmenopausal osteoporosis, therapy should be considered only for women at significant risk of osteoporosis and for whom non-estrogen medications are not considered to be appropriate. Patients should be treated with the lowest effective dose. Generally women should be started at 0.3 mg Premarin daily. Subsequent dosage adjustment may be made based upon the individual clinical and bone mineral density responses. This dose should be periodically reassessed by the healthcare provider.
   Premarin therapy may be given continuously with no interruption in therapy, or in cyclical regimens (regimens such as 25 days on drug followed by five days off drug) as is medically appropriate on an individualized basis.
3. For treatment of female hypoestrogenism due to hypogonadism, castration, or primary ovarian failure:
   Female hypogonadism--0.3 mg or 0.625 mg daily, administered cyclically (e.g., three weeks on and one week off). Doses are adjusted depending on the severity of symptoms and responsiveness of the endometrium.
   In clinical studies of delayed puberty due to female hypogonadism, breast development was induced by doses as low as 0.15 mg. The dosage may be gradually titrated upward at 6 to 12 month intervals as needed to achieve appropriate bone age advancement and eventual epiphyseal closure. Clinical studies suggest that doses of 0.15 mg, 0.3 mg, and 0.6 mg are associated with mean ratios of bone age advancement to chronological age progression ((DELTA)BA/(DELTA)CA) of 1.1, 1.5, and 2.1, respectively. (Premarin in the dose strength of 0.15 mg is not available commercially). Available data suggest that chronic dosing with 0.625 mg is sufficient to induce artificial cyclic menses with sequential progestin treatment and to maintain bone mineral density after skeletal maturity is achieved.
   Female castration or primary ovarian failure--1.25 mg daily, cyclically. Adjust dosage, upward or downward, according to severity of symptoms and response of the patient. For maintenance, adjust dosage to lowest level that will provide effective control.
4. For treatment of breast cancer, for palliation only, in appropriately selected women and men with metastatic disease:
   Suggested dosage is 10 mg three times daily for a period of at least three months.
5. For treatment of advanced androgen-dependent carcinoma of the prostate, for palliation only:
   1.25 mg to 2 × 1.25 mg three times daily. The effectiveness of therapy can be judged by phosphatase determinations as well as by symptomatic improvement of the patient.

HOW SUPPLIED

Premarin (conjugated estrogens tablets, USP)

• Each oval yellow tablet contains 1.25 mg, in bottles of 100 (NDC 0046-1104-81); and 1,000 (NDC 0046-1104-91).
• Each oval white tablet contains 0.9 mg, in bottles of 100 (NDC 0046-0864-81).
• Each oval maroon tablet contains 0.625 mg, in bottles of 100 (NDC 0046-0867-81); 1,000 (NDC 0046-0867-91); and Unit-Dose Packages of 100 (NDC 0046-0867-99).
• Each oval blue tablet contains 0.45 mg, in bottles of 100 (NDC 0046-0936-81).
• Each oval green tablet contains 0.3 mg, in bottles of 100 (NDC 0046-0868-81) and 1,000 (NDC 0046-0868-91).

The appearance of these tablets is a trademark of Wyeth Pharmaceuticals.

Store at 20-25° C (68-77° F); excursions permitted to 15-30° C (59-86° F) [see USP Controlled Room Temperature].

Dispense in a well-closed container as defined in the USP.

PRODUCT PHOTO(S):

PATIENT INFORMATION

(Updated April 2005)

Premarin ^®

(conjugated estrogens tablets, USP)

Read this PATIENT INFORMATION before you start taking Premarin and read what you get each time you refill Premarin. There may be new information. This information does not take the place of talking to your healthcare provider about your medical condition or your treatment.

What is Premarin?

Premarin is a medicine that contains a mixture of estrogen hormones.

Premarin is used after menopause to:

• reduce moderate to severe hot flashes. Estrogens are hormones made by a woman's ovaries. The ovaries normally stop making estrogens when a woman is between 45 and 55 years old. This drop in body estrogen levels causes the "change of life" or menopause (the end of monthly menstrual periods). Sometimes both ovaries are removed during an operation before natural menopause takes place. The sudden drop in estrogen levels causes "surgical menopause."
  When the estrogen levels begin dropping, some women get very uncomfortable symptoms, such as feelings of warmth in the face, neck, and chest, or sudden strong feelings of heat and sweating ("hot flashes" or "hot flushes"). In some women the symptoms are mild, and they will not need to take estrogens. In other women, symptoms can be more severe. You and your healthcare provider should talk regularly about whether you still need treatment with Premarin.
• treat moderate to severe dryness, itching, and burning, in and around the vagina. You and your healthcare provider should talk regularly about whether you still need treatment with Premarin to control these problems. If you use Premarin only to treat your dryness, itching, and burning in and around your vagina, talk with your healthcare provider about whether a topical vaginal product would be better for you.
• help reduce your chances of getting osteoporosis (thin weak bones). Osteoporosis from menopause is a thinning of the bones that makes them weaker and easier to break. If you use Premarin only to prevent osteoporosis from menopause, talk with your healthcare provider about whether a different treatment or medicine without estrogens might be better for you. You and your healthcare provider should talk regularly about whether you should continue with Premarin.
  Weight-bearing exercise, like walking or running, and taking calcium and vitamin D supplements may also lower your chances for getting postmenopausal osteoporosis. It is important to talk about exercise and supplements with your healthcare provider before starting them.

Premarin is also used to:

• treat certain conditions in women before menopause if their ovaries do not make enough estrogen naturally.
• ease symptoms of certain cancers that have spread through the body, in men and women.

Who should not take Premarin?

Do not start taking Premarin if you:

• have unusual vaginal bleeding.
• currently have or have had certain cancers. Estrogens may increase the chances of getting certain types of cancers, including cancer of the breast or uterus. If you have or have had cancer, talk with your healthcare provider about whether you should take Premarin.
• had a stroke or heart attack in the past year.
• currently have or have had blood clots.
• currently have liver problems.
• are allergic to Premarin tablets or any of its ingredients. See the end of this leaflet for a list of all the ingredients in Premarin.
• think you may be pregnant.

Tell your healthcare provider:

• if you are breast feeding. The hormones in Premarin can pass into your milk.
• about all of your medical problems. Your healthcare provider may need to check you more carefully if you have certain conditions, such as asthma (wheezing), epilepsy (seizures), migraine, endometriosis, lupus, problems with your heart, liver, thyroid, kidneys, or have high calcium levels in your blood.
• about all the medicines you take, including prescription and nonprescription medicines, vitamins, and herbal supplements. Some medicines may affect how Premarin works. Premarin may also affect how your other medicines work.
• if you are going to have surgery or will be on bedrest. You may need to stop taking estrogens.

How should I take Premarin?

• Take one Premarin tablet at the same time each day.
• If you miss a dose, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your normal schedule. Do not take 2 doses at the same time.
• Estrogens should be used at the lowest dose possible for your treatment only as long as needed. You and your healthcare provider should talk regularly (for example, every 3 to 6 months) about the dose you are taking and whether you still need treatment with Premarin.

What are the possible side effects of Premarin?

Less common but serious side effects include:

• Breast cancer
• Cancer of the uterus
• Stroke
• Heart attack
• Blood clots
• Dementia
• Gallbladder disease
• Ovarian cancer

These are some of the warning signs of serious side effects:

• Breast lumps
• Unusual vaginal bleeding
• Dizziness and faintness
• Changes in speech
• Severe headaches
• Chest pain
• Shortness of breath
• Pains in your legs
• Changes in vision
• Vomiting

Call your healthcare provider right away if you get any of these warning signs, or any other unusual symptom that concerns you.

Common side effects include:

• Headache
• Breast pain
• Irregular vaginal bleeding or spotting
• Stomach/abdominal cramps, bloating
• Nausea and vomiting
• Hair loss

Other side effects include:

• High blood pressure
• Liver problems
• High blood sugar
• Fluid retention
• Enlargement of benign tumors of the uterus ("fibroids")
• Vaginal yeast infections

These are not all the possible side effects of Premarin. For more information, ask your healthcare provider or pharmacist.

What can I do to lower my chances of getting a serious side effect with Premarin?

• Talk with your healthcare provider regularly about whether you should continue taking Premarin.
• If you have a uterus, talk to your healthcare provider about whether the addition of a progestin is right for you. In general, the addition of a progestin is recommended for women with a uterus to reduce the chance of getting cancer of the uterus.
• See your healthcare provider right away if you get vaginal bleeding while taking Premarin.
• Have a breast exam and mammogram (breast X-ray) every year unless your healthcare provider tells you something else. If members of your family have had breast cancer or if you have ever had breast lumps or an abnormal mammogram, you may need to have breast exams more often.
• If you have high blood pressure, high cholesterol (fat in the blood), diabetes, are overweight, or if you use tobacco, you may have higher chances for getting heart disease. Ask your healthcare provider for ways to lower your chances for getting heart disease.

General information about the safe and effective use of Premarin

Medicines are sometimes prescribed for conditions that are not mentioned in patient information leaflets. Do not take Premarin for conditions for which it was not prescribed. Do not give Premarin to other people, even if they have the same symptoms you have. It may harm them.

Keep Premarin out of the reach of children.

This leaflet provides a summary of the most important information about Premarin. If you would like more information, talk with your healthcare provider or pharmacist. You can ask for information about Premarin that is written for health professionals. You can get more information by calling the toll free number 800-934-5556.

What are the ingredients in Premarin?

Premarin contains a mixture of conjugated estrogens, which are a mixture of sodium estrone sulfate and sodium equilin sulfate and other components including sodium sulfate conjugates, 17 (alpha)-dihydroequilin, 17 (alpha)-estradiol, and 17 (beta)-dihydroequilin. Premarin 0.3 mg, 0.45 mg, 0.625 mg, and 0.9 mg tablets also contain the following inactive ingredients: calcium phosphate tribasic, calcium sulfate, carnauba wax, microcrystalline cellulose, powdered cellulose, glyceryl monooleate, lactose monohydrate, magnesium stearate, methylcellulose, pharmaceutical glaze, polyethylene glycol, stearic acid (not present in 0.45 mg tablet), sucrose, and titanium dioxide.

Premarin 1.25 mg tablets contain the following inactive ingredients: calcium phosphate tribasic, hydroxypropyl cellulose, microcrystalline cellulose, powdered cellulose, hypromellose, lactose monohydrate, magnesium stearate, polyethylene glycol, sucrose and titanium dioxide.

The tablets come in different strengths and each strength tablet is a different color. The color ingredients are:

• 0.3 mg tablet (green color): D&C Yellow No. 10, FD&C Blue No. 1, FD&C Blue No. 2, and FD&C Yellow No. 6.
• 0.45 mg tablet (blue color): FD&C Blue No. 2.
• 0.625 mg tablet (maroon color): FD&C Blue No. 2, D&C Red No. 27, and FD&C Red No. 40.
• 0.9 mg tablet (white color): D&C Red No. 6 and D&C Red No. 7.
• 1.25 mg tablet (yellow color): black iron oxide, D&C Yellow No. 10, and FD&C Yellow No. 6.

The appearance of these tablets is a trademark of Wyeth Pharmaceuticals.

This product's label may have been revised after this insert was used in production. For further product information and current package insert, please visit www.wyeth.com or call our medical communications department toll-free at 1-800-934-5556.

Wyeth ^®