Duavive (Conjugated Estrogens 0.45 mg / Bazedoxifene 20 mg)
Pharmacological Class
Mechanism of Action
| Component |
Mechanism |
Clinical Role |
| Conjugated Estrogens |
Bind estrogen receptors (ERα, ERβ) → gene transcription promoting estrogenic activity on tissues (bone, vasomotor center, urogenital tract). |
Relieves vasomotor symptoms and prevents post-menopausal bone loss. |
| Bazedoxifene |
SERM with estrogen antagonist activity on endometrial and breast tissue, and agonist activity on bone. |
Replaces the need for progestin by protecting the endometrium from unopposed estrogen stimulation. |
Result: Estrogenic benefits (bone, hot flashes relief) without endometrial hyperplasia risk typical of estrogen-only therapy in women with an intact uterus.
Indications (Health Canada / FDA)
- Moderate-to-severe vasomotor symptoms associated with menopause.
- Prevention of post-menopausal osteoporosis in women at risk.
Not for treatment of established osteoporosis or cardiovascular disease prevention.
Dose and Administration
| Parameter |
Recommendation |
| Formulation |
0.45 mg conjugated estrogens / 20 mg bazedoxifene per tablet |
| Usual Dose |
1 tablet orally once daily |
| Administration |
With or without food, at the same time each day |
| Missed Dose |
Take as soon as remembered; skip if almost time for next dose (do not double). |
Contraindications
- Undiagnosed abnormal genital bleeding
- Known, suspected, or history of estrogen-dependent malignancy (e.g., breast, endometrial)
- Active or past VTE, PE, or arterial thromboembolic disease (MI, stroke)
- Liver impairment or disease
- Known thrombophilic disorders (protein C/S or antithrombin deficiency)
- Pregnancy or breastfeeding
Warnings & Precautions
| System |
Key Concerns |
| Thromboembolism |
↑ risk of DVT, PE, stroke; avoid in women with risk factors. |
| Endometrial Safety |
Bazedoxifene antagonism mitigates hyperplasia risk, but monitor for unexplained bleeding. |
| Breast Safety |
Unknown long-term breast cancer risk—periodic screening recommended. |
| Cognitive |
Possible ↑ dementia risk in women ≥ 65 y. |
| Lipid/Metabolic |
Mild HDL↑ and LDL↓; monitor triglycerides if elevated pre-treatment. |
| Hepatic |
Use caution; both agents metabolized hepatically (primarily glucuronidation). |
Adverse Effects
| Common (≥5%) |
Serious / Rare |
| Muscle spasms, nausea, diarrhea, dyspepsia |
VTE, stroke, retinal vein thrombosis |
| Upper abdominal pain, oropharyngeal pain |
Gallbladder disease, hepatic dysfunction |
| Dizziness, neck pain, hot flush (paradoxical) |
New breast tenderness or mass |
Monitoring Parameters (Clinical Pharmacist Perspective)
| Parameter |
Frequency / Notes |
| BP and VTE risk assessment |
Baseline and periodically |
| Breast exam + mammography |
Baseline and per local guideline |
| Endometrial symptoms (bleeding) |
At each visit; investigate any abnormal bleeding |
| LFTs |
If symptomatic or history of liver disease |
| Lipid profile, bone mineral density |
Baseline, then periodically for long-term therapy |
| Response |
Relief of vasomotor symptoms (within weeks), improved BMD over months |
Pharmacokinetics Summary
| Parameter |
Conjugated Estrogens |
Bazedoxifene |
| Absorption |
Oral bioavailability moderate |
Poorly absorbed (~6%) |
| Metabolism |
Extensive hepatic conjugation |
Glucuronidation (UGT1A1, UGT2B7) |
| Half-life |
~17 h (for estrone) |
~30 h |
| Elimination |
Urine & bile |
Fecal (unchanged/metabolites) |
Drug Interactions
- Cholestyramine/Colestipol: ↓ absorption of both components.
- Strong UGT inducers (rifampin, carbamazepine, phenytoin): may ↓ bazedoxifene levels.
- Estrogen-containing products: avoid co-administration.
- Warfarin: possible alteration in anticoagulant effect (monitor INR).
Clinical Pearls
- Duavive is best suited for postmenopausal women with a uterus who require estrogen therapy but cannot or do not wish to use a progestin.
- Not indicated for women >75 years or with surgical menopause who prefer progestin-based regimens.
- Always use lowest effective dose for shortest duration consistent with treatment goals.
- Discontinue immediately if VTE, stroke, or visual disturbance occurs.
