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Estrogens (Conjugated/Equine) and Bazedoxifene

Pronunciation

(ES troe jenz, KON joo gate ed/EE kwine & ba ze DOX i feen)

Index Terms

  • Bazedoxifene and Estrogens (Conjugated/Equine)
  • Estrogens (Conjugated/Equine) and Bazedoxifene Acetate

Dosage Forms

Tablet, oral:

Duavee: Conjugated estrogens 0.45 mg and bazedoxifene 20 mg

Brand Names: U.S.

  • Duavee

Pharmacologic Category

  • Estrogen Derivative
  • Selective Estrogen Receptor Modulator (SERM)
  • Tissue-Selective Estrogen Complex (TSEC)

Pharmacology

Conjugated estrogens contain a mixture of estrone sulfate, equilin sulfate, 17 alpha-dihydroequilin, 17 alpha-estradiol and 17 beta-dihydroequilin. Bazedoxifene is a selective estrogen receptor modulator (SERM). Conjugated estrogens act as an estrogen agonist and bazedoxifene acts as an estrogen agonist/antagonist depending on the specific tissue. The combination of a SERM and estrogen [referred to as a tissue-selective estrogen complex (TSEC)] provides relief of vasomotor symptoms and maintenance of bone mineral density in postmenopausal women with a uterus, while reducing the risk of endometrial hyperplasia observed with estrogen use alone (Pickar, 2009).

Absorption

Conjugated estrogens: Well-absorbed from the gastrointestinal tract

Distribution

Bazedoxifene: Vd: ~15 L/kg

Metabolism

Bazedoxifene: Metabolized via glucuronidation; forms metabolites; little or no CYP mediated metabolism; undergoes hepatic recirculation

Conjugated estrogens: Hepatic via CYP3A4; estradiol is converted to estrone and estriol; also undergoes enterohepatic recirculation; estrone sulfate is the main metabolite in postmenopausal women

Excretion

Conjugated estrogens: Urine (primarily estriol, also as estradiol, estrone, and conjugates)

Bazedoxifene: Biliary; feces (~85%); urine (<1%)

Onset of Action

Relief of vasomotor symptoms: A significant reduction in the number and severity of moderate/severe hot flashes was observed after 4 weeks of therapy (Pinkerton, 2009).

Osteoporosis: A significant increase in BMD measured at the lumbar spine and hip was observed at 12 months of therapy (Lindsay, 2009).

Time to Peak

Bazedoxifene: ~2.5 hours

Total estrone: ~6.5 hours

Half-Life Elimination

Bazedoxifene: ~30 hours

Total estrone: ~17 hours

Protein Binding

Bazedoxifene: 98% to 99%; does not bind to sex-hormone binding globulin

Conjugated estrogens: Binds to sex-hormone-binding globulin and albumin

Use: Labeled Indications

Postmenopausal osteoporosis prophylaxis: Prevention of postmenopausal osteoporosis in women with a uterus

Vasomotor symptoms: Treatment of moderate-to-severe vasomotor symptoms associated with menopause in women with a uterus

Contraindications

Angioedema or anaphylactic reaction to estrogens, bazedoxifene, or any component of the formulation; undiagnosed abnormal uterine bleeding; active or past history of venous thromboembolism (VTE) (eg, PE, DVT); active or history of arterial thromboembolic disease (eg, stroke, MI); carcinoma of the breast (known, suspected or history of); estrogen-dependent tumor; hepatic impairment or disease; known protein C, protein S, or antithrombin deficiency or other known thrombophilic disorders; pregnancy or women who may become pregnant; breast-feeding

Dosing: Adult

Menopause (moderate-to-severe vasomotor symptoms), prevention of postmenopausal osteoporosis: Females: Oral: One tablet daily

Dosing: Geriatric

Refer to adult dosing. Use in women >75 years of age is not recommended (has not been studied).

Dosing: Renal Impairment

No dosage adjustment provided in manufacturer’s labeling (has not been studied). Use is not recommended.

Dosing: Hepatic Impairment

Use is contraindicated with hepatic dysfunction or disease.

Administration

Administer once daily, without regard to meals. Patient should swallow tablets whole.

Hazardous agent; use appropriate precautions for handling and disposal (NIOSH 2014 [group 2]).

Dietary Considerations

Ensure adequate calcium and vitamin D intake when used for the prevention of osteoporosis.

Storage

Store at 20°C to 25°C (68°F to 77°F); excursions are permitted between 15°C and 30°C (59°F and 86°F). Dispense in original package. Protect from moisture. After opening foil pouch, product must be used within 60 days.

Drug Interactions

Ajmaline: Estrogen Derivatives may enhance the adverse/toxic effect of Ajmaline. Specifically, the risk for cholestasis may be increased. Monitor therapy

Anastrozole: Estrogen Derivatives may diminish the therapeutic effect of Anastrozole. Avoid combination

Anthrax Immune Globulin (Human): Estrogen Derivatives may enhance the thrombogenic effect of Anthrax Immune Globulin (Human). Monitor therapy

Anticoagulants: Estrogen Derivatives may diminish the anticoagulant effect of Anticoagulants. More specifically, the potential prothrombotic effects of some estrogens and progestin-estrogen combinations may counteract anticoagulant effects. Management: Carefully weigh the prospective benefits of estrogens against the potential increased risk of procoagulant effects and thromboembolism. Use is considered contraindicated under some circumstances. Refer to related guidelines for specific recommendations. Consider therapy modification

Antidiabetic Agents: Hyperglycemia-Associated Agents may diminish the therapeutic effect of Antidiabetic Agents. Monitor therapy

Ascorbic Acid: May increase the serum concentration of Estrogen Derivatives. Monitor therapy

Bosentan: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

C1 inhibitors: Estrogen Derivatives may enhance the thrombogenic effect of C1 inhibitors. Monitor therapy

Cannabis: May decrease the serum concentration of CYP1A2 Substrates. Monitor therapy

Chenodiol: Estrogen Derivatives may diminish the therapeutic effect of Chenodiol. Management: Monitor clinical response to chenodiol closely when used together with any estrogen derivative. Monitor therapy

CloZAPine: CYP1A2 Inhibitors (Weak) may increase the serum concentration of CloZAPine. Monitor therapy

Corticosteroids (Systemic): Estrogen Derivatives may increase the serum concentration of Corticosteroids (Systemic). Monitor therapy

CYP1A2 Inducers (Strong): May increase the metabolism of CYP1A2 Substrates. Management: Consider an alternative for one of the interacting drugs. Some combinations may be specifically contraindicated. Consult appropriate manufacturer labeling. Consider therapy modification

CYP3A4 Inducers (Moderate): May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

CYP3A4 Inducers (Strong): May increase the metabolism of CYP3A4 Substrates. Management: Consider an alternative for one of the interacting drugs. Some combinations may be specifically contraindicated. Consult appropriate manufacturer labeling. Consider therapy modification

Cyproterone: May decrease the serum concentration of CYP1A2 Substrates. Monitor therapy

Dabrafenib: May decrease the serum concentration of CYP3A4 Substrates. Management: Seek alternatives to the CYP3A4 substrate when possible. If concomitant therapy cannot be avoided, monitor clinical effects of the substrate closely (particularly therapeutic effects). Consider therapy modification

Dantrolene: Estrogen Derivatives may enhance the hepatotoxic effect of Dantrolene. Monitor therapy

Deferasirox: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

Dehydroepiandrosterone: May enhance the adverse/toxic effect of Estrogen Derivatives. Avoid combination

Enzalutamide: May decrease the serum concentration of CYP3A4 Substrates. Management: Concurrent use of enzalutamide with CYP3A4 substrates that have a narrow therapeutic index should be avoided. Use of enzalutamide and any other CYP3A4 substrate should be performed with caution and close monitoring. Consider therapy modification

Exemestane: Estrogen Derivatives may diminish the therapeutic effect of Exemestane. Avoid combination

Hemin: Estrogen Derivatives may diminish the therapeutic effect of Hemin. Avoid combination

Herbs (Estrogenic Properties): May enhance the adverse/toxic effect of Estrogen Derivatives. Monitor therapy

Hyaluronidase: Estrogen Derivatives may diminish the therapeutic effect of Hyaluronidase. Management: Patients receiving estrogens (particularly at larger doses) may not experience the desired clinical response to standard doses of hyaluronidase. Larger doses of hyaluronidase may be required. Consider therapy modification

Immune Globulin: Estrogen Derivatives may enhance the thrombogenic effect of Immune Globulin. Monitor therapy

Indium 111 Capromab Pendetide: Estrogen Derivatives may diminish the diagnostic effect of Indium 111 Capromab Pendetide. Avoid combination

Lenalidomide: Estrogen Derivatives may enhance the thrombogenic effect of Lenalidomide. Monitor therapy

Mitotane: May decrease the serum concentration of CYP3A4 Substrates. Management: Doses of CYP3A4 substrates may need to be adjusted substantially when used in patients being treated with mitotane. Consider therapy modification

NSAID (COX-2 Inhibitor): May enhance the thrombogenic effect of Estrogen Derivatives. NSAID (COX-2 Inhibitor) may increase the serum concentration of Estrogen Derivatives. Monitor therapy

Ospemifene: Selective Estrogen Receptor Modulators may enhance the adverse/toxic effect of Ospemifene. Ospemifene may also enhance adverse/toxic effects of other Selective Estrogen Receptor Modulators. Selective Estrogen Receptor Modulators may diminish the therapeutic effect of Ospemifene. Ospemifene may also diminish the therapeutic effects of other Selective Estrogen Receptor Modulators. Avoid combination

Ospemifene: Estrogen Derivatives may enhance the adverse/toxic effect of Ospemifene. Estrogen Derivatives may diminish the therapeutic effect of Ospemifene. Avoid combination

Pomalidomide: May enhance the thrombogenic effect of Estrogen Derivatives. Management: Canadian pomalidomide labeling recommends caution with use of hormone replacement therapy and states that hormonal contraceptives are not recommended. US pomalidomide labeling does not contain these specific recommendations. Consider therapy modification

ROPINIRole: Estrogen Derivatives may increase the serum concentration of ROPINIRole. Monitor therapy

Siltuximab: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

Somatropin: Estrogen Derivatives may diminish the therapeutic effect of Somatropin. Shown to be a concern with oral hormone replacement therapy in postmenopausal women. Management: Monitor for reduced growth hormone efficacy. A larger somatropin dose may be required to reach treatment goal. This interaction does not appear to apply to non-orally administered estrogens (e.g., transdermal, vaginal ring). Consider therapy modification

St John's Wort: May decrease the serum concentration of CYP3A4 Substrates. Management: Consider an alternative for one of the interacting drugs. Some combinations may be specifically contraindicated. Consult appropriate manufacturer labeling. Consider therapy modification

Teriflunomide: May decrease the serum concentration of CYP1A2 Substrates. Monitor therapy

Thalidomide: Estrogen Derivatives may enhance the thrombogenic effect of Thalidomide. Monitor therapy

Theophylline Derivatives: Estrogen Derivatives may increase the serum concentration of Theophylline Derivatives. Exceptions: Dyphylline. Monitor therapy

Thyroid Products: Estrogen Derivatives may diminish the therapeutic effect of Thyroid Products. Monitor therapy

Tipranavir: Estrogen Derivatives may enhance the dermatologic adverse effect of Tipranavir. The combination of tipranavir/ritonavir and ethinyl estradiol/norethindrone was associated with a high incidence of skin rash. Tipranavir may decrease the serum concentration of Estrogen Derivatives. Management: Women using hormonal contraceptives should consider alternative, non-hormonal forms of contraception. Consider therapy modification

TiZANidine: CYP1A2 Inhibitors (Weak) may increase the serum concentration of TiZANidine. Management: Avoid these combinations when possible. If combined use cannot be avoided, initiate tizanidine at an adult dose of 2 mg and increase in 2-4 mg increments based on patient response. Monitor for increased effects of tizanidine, including adverse reactions. Consider therapy modification

Tocilizumab: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

Ursodiol: Estrogen Derivatives may diminish the therapeutic effect of Ursodiol. Monitor therapy

Adverse Reactions

Percentages as reported with combination product.

1% to 10%:

Central nervous system: Dizziness (5%)

Gastrointestinal: Diarrhea (8%), nausea (8%), dyspepsia (7%), upper abdominal pain (7%)

Neuromuscular & skeletal: Muscle spasm (9%), neck pain (5%)

Respiratory: Oropharyngeal pain (7%)

ALERT: U.S. Boxed Warning

Endometrial cancer:

There is an increased risk of endometrial cancer in a woman with a uterus who uses unopposed estrogens. Conjugated estrogens/bazedoxifene has been shown to reduce the risk of endometrial hyperplasia, which may be a precursor to endometrial cancer. Perform adequate diagnostic measures, including directed or random endometrial sampling when indicated, to rule out malignancy in postmenopausal women with undiagnosed persistent or recurring abnormal genital bleeding.

Cardiovascular disease:

Do not use estrogen therapy for the prevention of cardiovascular disease.

The Women's Health Initiative (WHI) estrogen-alone substudy reported increased risks of stroke and deep vein thrombosis (DVT) in postmenopausal women (50 to 79 years of age) during 7.1 years of treatment with daily oral conjugated estrogens (0.625 mg) alone, relative to placebo.

Dementia:

The WHI Memory Study (WHIMS) estrogen-alone ancillary study of WHI reported an increased risk of probable dementia in postmenopausal women 65 years and older during 5.2 years of treatment with daily conjugated estrogens (0.625 mg) alone, relative to placebo. It is unknown whether this finding applies to younger postmenopausal women.

Risk vs benefit:

Women taking conjugated estrogens/bazedoxifene should not take additional estrogens.In the absence of comparable data, these risks should be assumed to be similar for other doses of conjugated estrogens and other dosage forms of estrogens. Estrogens should be prescribed at the lowest effective doses and for the shortest duration consistent with treatment goals and risks for the individual woman.

Warnings/Precautions

Concerns related to adverse effects:

• Breast cancer: Based on data from the Women’s Health Initiative (WHI) studies, an increased risk of invasive breast cancer was not observed in postmenopausal women using conjugated estrogens (CE) alone. An increase in abnormal mammogram findings has been reported with estrogen alone.

• Dementia: [U.S. Boxed Warning]: In the Women’s Health Initiative Memory Study (WHIMS), an increased incidence of probable dementia was observed in women ≥65 years of age taking CE alone. It is not known if this finding applies to younger postmenopausal women. Estrogens should not be used for the prevention of dementia.

• Endometrial cancer: [U.S. Boxed Warning]: The use of unopposed estrogen in women with an intact uterus is associated with an increased risk of endometrial cancer. Estrogens (conjugated/equine) in combination with bazedoxifene has been shown to decrease the risk of endometrial hyperplasia, a precursor to endometrial cancer. Adequate diagnostic measures, including endometrial sampling if indicated, should be performed to rule out malignancy in postmenopausal women with undiagnosed abnormal vaginal bleeding. Women taking this combination should not take additional estrogen (may increase the risk of endometrial hyperplasia).

• Inherited thrombophilia: Women with inherited thrombophilias (eg, protein C or S deficiency) may have increased risk of venous thromboembolism (DeSancho, 2010; van Vlijmen, 2011). Use is contraindicated in women with protein C, protein S, antithrombin deficiency, or other known thrombophilic disorders.

• Lipid effects: Estrogen compounds are generally associated with lipid effects such as increased HDL-cholesterol and decreased LDL-cholesterol. Triglycerides may also be increased; discontinue if pancreatitis occurs.

• Ovarian cancer: Postmenopausal estrogen therapy may increase the risk of ovarian cancer; however, studies are not consistent, and the effects of this combination product on the risk of ovarian cancer are not known. Although the risk of ovarian cancer is rare, women who are at an increased risk (eg, family history) should be counseled about the association (NAMS, 2012).

• Retinal vascular thrombosis: Estrogens may cause retinal vascular thrombosis; discontinue pending examination if migraine, loss of vision, proptosis, diplopia, or other visual disturbances occur; discontinue permanently if papilledema or retinal vascular lesions are observed on examination.

Disease-related concerns:

• Asthma: Use caution in patients with asthma; may exacerbate disease.

• Carbohydrate intolerance: May have adverse effects on glucose tolerance; use caution in women with diabetes.

• Cardiovascular disease: [U.S. Boxed Warning]: Estrogens should not be used to prevent cardiovascular disease. Using data from the Women’s Health Initiative (WHI) studies, an increased risk of deep vein thrombosis (DVT) and stroke has been reported with CE in postmenopausal women 50-79 years of age. Estrogens and bazedoxifene are known to increase the risk of venous thromboembolism (VTE). Additional risk factors include diabetes mellitus, hypercholesterolemia, hypertension, SLE, obesity, tobacco use, and/or history of VTE. Risk factors should be managed appropriately; discontinue use if adverse cardiovascular events occur or are suspected.

• Diseases exacerbated by fluid retention: Use with caution in patients with diseases which may be exacerbated by fluid retention, including cardiac or renal dysfunction.

• Epilepsy: Use caution with epilepsy; may exacerbate disease.

• Gallbladder disease: Use of postmenopausal estrogen may be associated with an increased risk of gallbladder disease requiring surgery.

• Hepatic dysfunction: Estrogens are poorly metabolized in patients with hepatic dysfunction. Use caution with a history of cholestatic jaundice associated with prior estrogen use or pregnancy. Discontinue if jaundice develops or if acute or chronic hepatic disturbances occur. Use is contraindicated with hepatic disease.

• Hepatic hemangiomas: Use with caution in patients with hepatic hemangiomas; may exacerbate disease.

• Hereditary angioedema: Exogenous estrogens may exacerbate angioedema symptoms in women with hereditary angioedema.

• Hypoparathyroidism: Use caution in patients with hypoparathyroidism; estrogen-induced hypocalcemia may occur.

• Migraine: Use caution with migraine; may exacerbate disease.

• Porphyria: Use with caution in patients with porphyria; may exacerbate disease.

• SLE: Use with caution in patients with SLE; may exacerbate disease.

Concurrent drug therapy issues:

• Thyroid replacement therapy: Estrogens may increase thyroid-binding globulin (TBG) levels leading to increased circulating total thyroid hormone levels. Women on thyroid replacement therapy may require higher doses of thyroid hormone while receiving estrogens.

Special populations:

• Overweight/Obese: Bazedoxifene exposure is decreased in women with a BMI >27 kg/m2 which may be associated with an increased risk of endometrial hyperplasia. Women with a BMI >34 kg/m2 or >32.2 kg/m2 were excluded from some initial vasomotor or osteoporosis studies, respectively (Lindsay, 2009; Pinkerton, 2009). Regardless of BMI, monitoring should be done to rule out malignancy in postmenopausal women with undiagnosed persistent or recurrent abnormal genital bleeding.

• Surgical patients: Whenever possible, estrogens should be discontinued at least 4-6 weeks prior to elective surgery associated with an increased risk of thromboembolism or during periods of prolonged immobilization.

Special handling:

• Hazardous agent: Use appropriate precautions for handling and disposal (NIOSH 2014 [group 2]).

Other warnings/precautions:

• Laboratory changes: The use of estrogens and/or progestins may change the results of some laboratory tests (eg, coagulation factors, lipids, glucose tolerance, binding proteins). The dose, route, and the specific estrogen/progestin influences these changes. In addition, personal risk factors (eg, cardiovascular disease, smoking, diabetes, age) also contribute to adverse events; use of specific products may be contraindicated in women with certain risk factors.

• Osteoporosis use: For use only in women at significant risk of osteoporosis and for who other nonestrogen medications are not considered appropriate.

• Risks vs benefits: [U.S. Boxed Warning]: Women taking estrogens (conjugated/equine) in combination with bazedoxifene should not take additional estrogen. Estrogens should be used for the shortest duration possible at the lowest effective dose consistent with treatment goals. Women taking this combination should also not take progestins or additional estrogen agonists/antagonists. Before prescribing estrogen therapy to postmenopausal women, the risks and benefits must be weighed for each patient. Women should be informed of these risks and benefits. Patients should be reevaluated as clinically appropriate to determine if treatment is still necessary. Available data related to treatment risks are from Women’s Health Initiative (WHI) studies, which evaluated oral CE 0.625 mg relative to placebo in postmenopausal women. Other combinations and dosage forms of estrogens were not studied; outcomes should be assumed to be similar for other doses and other dosage forms of estrogens until comparable data becomes available.

Monitoring Parameters

Routine physical examination that includes blood pressure and Papanicolaou smear, breast exam, mammogram. Adequate diagnostic measures, including endometrial sampling, if indicated, should be performed to rule out malignancy in all cases of undiagnosed abnormal vaginal bleeding. Monitor for loss of vision, sudden onset of proptosis, diplopia, migraine; signs and symptoms of thromboembolic disorders; glycemic control in patients with diabetes; lipid profiles in patients being treated for hyperlipidemias; thyroid function in patients on thyroid hormone replacement therapy.

Menopausal symptoms: Periodically assess need for therapy.

Prevention of osteoporosis: Bone density measurement

Pregnancy Risk Factor

X

Pregnancy Considerations

Animal reproduction studies have not been conducted with this combination. This combination product is approved for use in postmenopausal women only. Use is contraindicated in women who are or who may become pregnant.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience muscle spasms, diarrhea, throat pain, neck pain, cramps, or bloating. Have patient report immediately to prescriber signs of severe cerebrovascular disease (change in strength on one side is greater than the other, difficulty speaking or thinking, change in balance, or vision changes), signs of DVT (edema, warmth, numbness, change in color, or pain in the extremities), signs of liver problems (dark urine, fatigue, lack of appetite, nausea, abdominal pain, light-colored stools, vomiting, or jaundice), angina, shortness of breath, coughing up blood, severe headache, severe dizziness, passing out, severe nausea, vomiting, severe abdominal pain, vaginitis, vaginal bleeding, bulging eyes, contact lens discomfort, vision changes, lump in breast, breast soreness or pain, nipple discharge, depression, mood changes, or memory impairment (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

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