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 conjugated estrogens (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 (14.5)].
Subgroup analyses of women 50 to 59 years of age suggest no increased risk of stroke for those women receiving conjugated estrogens (0.625 mg)-alone versus those receiving placebo (18 versus 21 per 10,000 women-years).
Should a stroke occur or be suspected, DUAVEE should be discontinued immediately [see Contraindications (4)].
Coronary Heart Disease
In the WHI estrogen-alone substudy, no overall effect on coronary heart disease (CHD) events (defined as nonfatal myocardial infarction, silent myocardial infarction, or CHD death) was reported in women receiving estrogen-alone compared to placebo [see Clinical Studies (14.5)].
Subgroup analyses of women 50 to 59 years of age suggest a statistically non-significant reduction in CHD events (CE [0.625 mg]-alone compared to placebo) in women with less than 10 years since menopause (8 versus 16 per 10,000 women-years).
Venous Thromboembolism (VTE)
In the WHI estrogen-alone substudy, the risk of VTE [DVT and pulmonary embolism (PE)] was increased for women receiving daily conjugated estrogens (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 [see Clinical Studies (14.5)].
If feasible, DUAVEE 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. Because immobilization increases the risk for venous thromboembolic events independent of therapy, DUAVEE should be discontinued prior to and during prolonged immobilization (e.g., post-surgical recovery, prolonged bed rest) and DUAVEE therapy should be resumed only after the patient is fully ambulatory. In addition, women taking DUAVEE should be advised to move about periodically during travel involving prolonged immobilization.
Endometrial Cancer
An increased risk of endometrial cancer has been reported with the use of unopposed estrogen therapy in women 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 use of estrogens for less than 1 year. The greatest risk appears associated with prolonged use, with increased risks of 15- to 24-fold for 5 to 10 years or more of treatment. This risk has been shown to persist for at least 8 to 15 years after estrogen therapy is discontinued.
DUAVEE contains an estrogen agonist/antagonist. This component reduces the risk of endometrial hyperplasia that can occur with the conjugated estrogens component. Endometrial hyperplasia may be a precursor to endometrial cancer. Women taking DUAVEE should not take additional estrogens as this may increase the risk of endometrial hyperplasia.
Clinical surveillance of all women taking DUAVEE 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.
Breast Cancer
The most important randomized clinical study providing information about breast cancer in estrogen-alone users is the WHI substudy of daily conjugated estrogens (0.625 mg)-alone. In the WHI estrogen-alone substudy, after an average follow-up of 7.1 years, daily conjugated estrogen (0.625 mg)-alone was not associated with an increased risk of invasive breast cancer (relative risk [RR] 0.80).
The use of estrogen-alone has been reported to result in an increase in abnormal mammograms requiring further evaluation. The effect of treatment with DUAVEE on the risk of breast cancer is unknown.
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
A meta-analysis of 17 prospective and 35 retrospective epidemiology studies found that women who used hormonal therapy for menopausal symptoms had an increased risk for ovarian cancer. The primary analysis, using case-control comparisons, included 12,110 cancer cases from the 17 prospective studies. The relative risks associated with current use of hormonal therapy was 1.41 (95% confidence interval [CI] 1.32 to 1.50); there was no difference in the risk estimates by duration of the exposure (less than 5 years [median of 3 years] vs. greater than 5 years [median of 10 years] of use before the cancer diagnosis). The relative risk associated with combined current and recent use (discontinued use within 5 years before cancer diagnosis) was 1.37 (95% CI 1.27–1.48), and the elevated risk was significant for both estrogen-alone and estrogen plus progestin products. The exact duration of hormone therapy use associated with an increased risk of ovarian cancer, however, is unknown.
The effect of treatment with DUAVEE on the risk of ovarian cancer is unknown.
Venous thromboembolism: In the clinical studies with DUAVEE, the reporting rates for venous thromboembolism (deep venous thrombosis, pulmonary embolism, and retinal vein thrombosis) were low in all treatment groups. Adverse reactions of venous thromboembolism were reported in 0.0% of patients treated with DUAVEE and 0.1% of patients treated with placebo. Due to the low rate of events in both groups, it is not possible to conclude that the risk of venous thromboembolism with DUAVEE is different from that seen with other estrogen therapies [see Warnings and Precautions (5.2)].
Risk Summary
DUAVEE is contraindicated for use in pregnant women and is not indicated for use in females of reproductive potential [see Contraindications (4), Warnings and Precautions (5.15)].
Conjugated Estrogens (CE)
There are no data with the use of conjugated estrogens in pregnant women; however, epidemiologic studies and meta-analyses have not found an increased risk of genital and non-genital birth defects (including cardiac anomalies and limb-reduction defects) following exposure to combined hormonal contraceptives before conception or during early pregnancy.
Bazedoxifene
There are no available data on bazedoxifene use in pregnant women to inform a drug associated risk of adverse developmental outcomes. Animal studies have shown that oral bazedoxifene administered during the period of organogenesis to pregnant rats or rabbits at 0.3 and 2 times, respectively, the exposure at the maximum recommended dose, can cause fetal harm [see Data]. Based on mechanism of action, bazedoxifene may block the important functions that estrogen has during all stages of pregnancy [see Clinical Pharmacology (12.1)].
Data
Animal data
Bazedoxifene
Administration of bazedoxifene to rats at maternally toxic dosages ≥1 mg/kg/day (≥ 0.3 times the human area under the curve (AUC) at the 20 mg dose) resulted in reduced numbers of live fetuses and/or reductions in fetal body weights. No fetal developmental anomalies were observed. In studies conducted with pregnant rabbits treated with bazedoxifene, abortion and an increased incidence of heart (ventricular septal defect) and skeletal system (ossification delays, misshapen or misaligned bones, primarily of the spine and skull) anomalies in the fetuses were present at maternally toxic dosages of ≥ 0.5 mg/kg/day (≥ 2 times the human AUC at the 20 mg dose).
Risk Summary
DUAVEE is not indicated for use in females of reproductive potential [see Warnings and Precautions (5.15)].
Conjugated Estrogens
Estrogens are present in human milk and can reduce milk production in breast-feeding females. This reduction can occur at any time but is less likely to occur once breast-feeding is well-established.
Bazedoxifene
There are no data on the presence of bazedoxifene in either human or animal breast milk, the effect on the breastfed infant, or the effects on milk production. Based on mechanism of action, bazedoxifene may block the important functions that estrogen has in mammary tissue during lactation [see Clinical Pharmacology (12.1)].
Infertility
Bazedoxifene
Based on animal data, bazedoxifene administration may adversely affect female fertility. However, clinical fertility studies with bazedoxifene have not been conducted [see Nonclinical Toxicology (13.1)].
Absorption
Following administration of multiple doses of conjugated estrogens 0.45 mg/bazedoxifene 20 mg to healthy women who were naturally postmenopausal or who had undergone bilateral oophorectomy, the mean steady state pharmacokinetic parameters at Day 10 for conjugated estrogens (baseline adjusted for total estrone) and bazedoxifene are summarized in Table 2.
Table 2: Mean ± SD Steady-State Pharmacokinetic Parameters (n=24) | Cmax (ng/mL) | Tmax (hr) | AUCss (ng∙hr/mL) |
|---|
| Baseline-Adjusted Total Estrone | 2.6 ± 0.8 | 6.5 ± 1.6 | 35 ± 12 |
| Bazedoxifene | 6.9 ± 3.9 | 2.5 ± 2.1 | 71 ± 34 |
Results from monotherapy studies with conjugated estrogens or bazedoxifene components of DUAVEE, are noted below:
Conjugated estrogens are soluble in water and are well-absorbed from the gastrointestinal tract after release from the drug formulation.
Bazedoxifene exhibits a linear increase in plasma concentrations for single doses from 0.5 mg up to 120 mg and multiple daily doses from 1 mg to 80 mg. The absolute bioavailability of bazedoxifene is approximately 6%.
Food Effect
In a single-dose, crossover study in 23 postmenopausal women given conjugated estrogens 0.625 mg/bazedoxifene 20 mg with a high fat/high calorie meal, food increased AUC0–inf of bazedoxifene by 25%. The Cmax of bazedoxifene was unchanged.
Distribution
The distribution of conjugated estrogens and bazedoxifene after administration of DUAVEE has not been studied.
Results from monotherapy studies with conjugated estrogens or bazedoxifene, components of DUAVEE, are noted below:
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.
Following intravenous (IV) administration of a 3 mg dose of bazedoxifene, the volume of distribution is 14.7 ± 3.9 L/kg. Bazedoxifene is highly bound (98%–99%) to plasma proteins in vitro, but does not bind to SHBG.
Metabolism
The metabolic disposition of conjugated estrogens and bazedoxifene, after administration of DUAVEE, has not been studied.
Results from monotherapy studies with conjugated estrogens or bazedoxifene, components of DUAVEE, are noted below:
Exogenous estrogens are metabolized in the same manner as endogenous estrogens. Circulating estrogens exist in a dynamic equilibrium of metabolic interconversions. 17-β estradiol is converted reversibly to estrone, and both can be converted to estriol, which is the major urinary metabolite. 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.
The metabolic disposition of bazedoxifene has been determined following oral administration of 20 mg of radiolabeled bazedoxifene. Bazedoxifene is extensively metabolized in women. Glucuronidation is the major metabolic pathway. Little or no cytochrome P450-mediated metabolism is evident. Bazedoxifene-5-glucuronide is the major circulating metabolite. The concentrations of this glucuronide are approximately 10-fold higher than those of unchanged drug in plasma.
Excretion
After administration of a single dose of conjugated estrogens/bazedoxifene, baseline-adjusted total estrone (representing conjugated estrogens) is eliminated with a half-life of approximately 17 hours. Bazedoxifene is eliminated with a half-life of approximately 30 hours. Steady-state concentrations are achieved by the second week of once-daily administration.
Results from monotherapy studies with conjugated estrogens or bazedoxifene, components of DUAVEE, are noted below:
The conjugated estrogens components, 17β-estradiol, estrone, and estriol are excreted in the urine, along with glucuronide and sulfate conjugates.
The clearance of bazedoxifene is 0.4 ± 0.1 L/h/kg based on intravenous administration. The major route of excretion after oral administration of 20 mg of radiolabeled bazedoxifene is via biliary excretion, followed by elimination in the feces (~85%), with < 1% of the radioactive dose eliminated in the urine. Based on these results, it is expected that bazedoxifene undergoes entero-hepatic recycling from the gut back to the systemic circulation, therefore, some drugs may potentially interfere with bazedoxifene recycling process in the gut by various mechanisms resulting in a decrease in its systemic exposure.
Use in Specific Populations
Pediatric
The pharmacokinetics of conjugated estrogens/bazedoxifene tablets have not been evaluated in a pediatric population [see Use in Specific Populations (8.4)].
Geriatric
The effect of age on the pharmacokinetics of conjugated estrogens/bazedoxifene tablets have not been evaluated [see Use in Specific Populations (8.5)].
No pharmacokinetic studies with conjugated estrogens were conducted in specific populations, including women over 75 years of age.
The pharmacokinetics of a 20 mg single-dose of bazedoxifene, were evaluated in postmenopausal women. On average, compared to women 51 to 64 years of age (n=8), women 65 to 74 years of age (n=8) showed a 1.5-fold increase in AUC, and women ≥ 75 years of age (n=8) showed a 2.6-fold increase in AUC.
Renal Impairment
The pharmacokinetics of conjugated estrogens/bazedoxifene tablets have not been evaluated in women with renal impairment [see Dosage and Administration (2.6) and Use in Specific Populations (8.6)].
Hepatic Impairment
The pharmacokinetics of conjugated estrogens/bazedoxifene tablets have not been evaluated in women with hepatic impairment [see Contraindications (4), Warnings and Precautions (5.5), and Use in Specific Populations (8.7)].
No pharmacokinetic studies with conjugated estrogens were conducted in specific populations, including women with hepatic impairment.
A single dose of bazedoxifene 20 mg was given to fasted, healthy (N=18) and hepatically impaired postmenopausal women. In six mild hepatic impairment patients (Child Pugh Class A), Cmax and AUC of bazedoxifene increased 67% and 143%, respectively, compared to healthy subjects. In six moderate hepatic impairment patients (Child Pugh Class B), Cmax and AUC of bazedoxifene increased 32% and 109%, respectively, compared to healthy subjects. In six severe hepatic impairment patients (Child Pugh Class C), Cmax and AUC of bazedoxifene increased 20% and 268%, respectively, compared to healthy subjects. Half-life was prolonged from 32 to 50 hrs in patients with severe hepatic impairment, compared to healthy subjects.
Body Mass Index
In a clinical study, a single dose of DUAVEE (conjugated estrogens 0.45 mg/bazedoxifene 20 mg) was administered to 12 obese [mean (SD) BMI = 32.7 (2.7) kg/m2] and 12 non-obese [mean (SD) BMI = 25.3 (2.6) kg/m2] postmenopausal women. In obese subjects, systemic exposure (AUC0–72) of total estrone was 2% lower and systemic exposures (AUC0–inf) of total equilin and bazedoxifene were 32% and 13% lower, respectively, compared to non-obese subjects.
Drug Interactions
Effect of Co-Administered Drugs on the Pharmacokinetics of Conjugated Estrogens/Bazedoxifene
In a drug-drug interaction study, itraconazole 200 mg, a strong CYP3A4 inhibitor, was administered with breakfast to 24 postmenopausal women for 4 days, followed by a fifth dose of itraconazole 200 mg with breakfast and DUAVEE on Day 5 (3 hours after itraconazole). Itraconazole 200 mg was continued for 2 additional days after the co-administration of itraconazole 200 mg and DUAVEE. Following co-administration of DUAVEE and itraconazole, baseline-adjusted total estrone Cmax and AUC0–72 increased 9% and 9%, respectively, total equilin Cmax and AUC0–72 increased 11% and 5%, respectively, and bazedoxifene Cmax and AUC0–inf increased 11% and 40%, respectively, compared to subjects treated with DUAVEE alone.
Effect of Co-Administered Drugs on the Pharmacokinetics of Bazedoxifene
Conjugated Estrogens
Conjugated estrogens 0.625 mg were administered alone for 6 consecutive days prior to the co-administration of a single dose of 20 mg bazedoxifene and conjugated estrogens 0.625 mg in thirty postmenopausal women. Conjugated estrogens 0.625 mg were continued for 2 additional days after the co-administration of bazedoxifene and conjugated estrogens. The Cmax of bazedoxifene increased by 3% and AUC of bazedoxifene decreased by 6%.
Ibuprofen
A single dose of ibuprofen 600 mg was given with a bazedoxifene 20 mg capsule in twelve postmenopausal women after an overnight fast. Co-administration of ibuprofen and bazedoxifene increased Cmax and AUC of bazedoxifene by 18% and 7%, respectively.
Atorvastatin
Atorvastatin 20 mg was given once with bazedoxifene 40 mg in thirty postmenopausal women. Co-administration of atorvastatin and bazedoxifene decreased Cmax of bazedoxifene by 3% and increased AUC of bazedoxifene by 6%.
Azithromycin
Azithromycin 500 mg was given once daily for 8 consecutive days in thirty postmenopausal women. Azithromycin 500 mg and a bazedoxifene 40 mg tablet were co-administered on Day 9. Azithromycin 250 mg administration once daily continued on Days 10 to 13. Co-administration of azithromycin and bazedoxifene increased Cmax of bazedoxifene by 6% and decreased AUC of bazedoxifene by 15%.
Aluminum and Magnesium Hydroxide
A single dose of 460 mg aluminum hydroxide and 400 mg magnesium hydroxide was given with a bazedoxifene 40 mg tablet in thirty postmenopausal women after an overnight fast. Co-administration of aluminum/magnesium hydroxide and bazedoxifene decreased Cmax of bazedoxifene by 8% and increased AUC of bazedoxifene by 7%.
Effect of Bazedoxifene on the Pharmacokinetics of Co-Administered Drugs
Conjugated Estrogens
Bazedoxifene 20 mg was administered alone for 8 consecutive days prior to co-administration of a single dose of conjugated estrogens 0.625 mg and bazedoxifene 20 mg in twenty-six postmenopausal women. Bazedoxifene 20 mg was continued for 2 additional days after co-administration of bazedoxifene and conjugated estrogens. The Cmax and AUC of unconjugated estrone increased by 11% and 3%, respectively. The Cmax and AUC of unconjugated equilin increased by 17% and 14%, respectively.
Ibuprofen
A single dose of bazedoxifene 20 mg capsule was given with a single dose of ibuprofen 600 mg in twelve fasted, postmenopausal women. Co-administration of bazedoxifene and ibuprofen increased the Cmax of ibuprofen by 6%. The AUC of ibuprofen was unchanged.
Atorvastatin
Bazedoxifene 40 mg was given for 8 consecutive days prior to co-administration of bazedoxifene 40 mg and atorvastatin 20 mg. Co-administration of bazedoxifene and atorvastatin decreased Cmax of atorvastatin by 14%. The AUC of atorvastatin was unchanged. The Cmax and AUC of 2-OH atorvastatin were decreased by 18% and 8%, respectively.
Carcinogenesis
Carcinogenicity studies with conjugated estrogens/bazedoxifene have not been conducted.
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 6-month oral gavage carcinogenicity studies of bazedoxifene in transgenic Tg.RasH2 mice, there was a drug-related increased incidence of benign, ovarian granulosa-cell tumors in female mice given 150 or 500 mg/kg/day. In a two-year dietary carcinogenicity study of bazedoxifene in rats (administered at 0.003%, 0.01%, 0.03%, or 0.1%) a drug-related marked increased incidence of benign, ovarian granulosa-cell tumors was observed in female rats at concentrations of 0.03% and 0.1%. Systemic exposure (AUC) of bazedoxifene in these groups was 3 and 8 times that observed in postmenopausal women administered 20 mg/day. In male rats, drug-related renal tumors (adenomas and carcinomas), in the presence of renal toxicity, were observed at all doses tested, which corresponded to exposure ratios of 0.06 to 5 times the clinical AUC at a dose of 20 mg.
Mutagenesis
Mutagenicity studies with conjugated estrogens/bazedoxifene have not been conducted.
Bazedoxifene was not genotoxic or mutagenic in a battery of tests, including in vitro bacterial reverse mutation assay, in vitro mammalian cell forward mutation assay at the thymidine kinase (TK+/-) locus in L5178Y mouse lymphoma cells, in vitro chromosome aberration assay in Chinese hamster ovary (CHO) cells, and in vivo mouse micronucleus assay.
Impairment of Fertility
Impairment of fertility studies with conjugated estrogens/bazedoxifene have not been conducted.
Female rats were administered daily dosages of 0.3 to 30 mg/kg bazedoxifene (0.03 to 10 times human AUC at the 20 mg dose) prior to and during mating with untreated males. Estrous cycles and fertility were adversely affected in all bazedoxifene-treated female groups.
Blisters
DUAVEE tablets should be stored at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F). See USP Controlled Room Temperature. Dispense product in the original package. Tablets should not be removed from blisters until immediately before use. Protect from moisture. After opening foil pouch, product must be used within 60 days.
This product's label may have been updated. For current full prescribing information, please visit www.pfizer.com.
LAB-0582-6.0