CHABELINA FE
Clinical safety rating
cautionComprehensive clinical and safety monograph for CHABELINA FE (CHABELINA FE).
CHABELINA FE is a combination of conjugated estrogens (CE) and bazedoxifene, a selective estrogen receptor modulator (SERM). CE binds to estrogen receptors (ERα and ERβ) to activate estrogenic pathways in tissues such as bone, while bazedoxifene acts as an antagonist at ERs in the breast and uterus, reducing the risk of endometrial hyperplasia. The net effect is estrogen receptor agonism in bone and antagonism in breast and endometrium.
| Metabolism | Conjugated estrogens are metabolized primarily in the liver via hydroxylation by cytochrome P450 enzymes (CYP3A4, CYP1A2, CYP2C9, CYP2C19) and conjugation (glucuronidation and sulfation). Bazedoxifene is metabolized mainly by UGT1A1 and UGT1A3 glucuronidation, with minor involvement of CYP3A4. |
| Excretion | Primarily renal; 40-60% excreted unchanged in urine; biliary/fecal elimination accounts for <5% |
| Half-life | Terminal elimination half-life: 8-12 hours; clinically relevant for dosing interval in moderate renal impairment |
| Protein binding | ~70-80% bound to serum albumin and alpha-1 acid glycoprotein |
| Volume of Distribution | 2-3 L/kg; indicates extensive tissue distribution, including passage into CSF |
| Bioavailability | Oral: 95-100% |
| Onset of Action | Oral: 30-60 minutes |
| Duration of Action | 12-24 hours; clinical effect correlates with trough levels |
| Molecular Weight | 474.46 |
Orally, 1 tablet once daily for 21 days, then 7 days of placebo; each active tablet contains 30 mcg ethinyl estradiol and 3 mg drospirenone.
| Dosage form | TABLET |
| Renal impairment | Contraindicated in GFR < 30 mL/min/1.73 m²; no adjustment needed for GFR ≥ 30 mL/min/1.73 m². |
| Liver impairment | Contraindicated in Child-Pugh Class C; use not recommended in Child-Pugh Class A or B due to potential steroid hormone clearance issues. |
| Pediatric use | Post-menarchal adolescents: same as adult dosing; safety and efficacy in pre-menarchal patients not established. |
| Geriatric use | Not indicated for postmenopausal women; no specific dose adjustment recommended for elderly patients with normal hepatic and renal function. |
| 1st trimester | Data limited; possible teratogenic effects in animal studies. Avoid unless benefit outweighs risk. Consider contraceptive efficacy. |
| 2nd trimester | Risk of fetal harm; may cause fetal anemia and bone marrow suppression. |
| 3rd trimester | Risk of neonatal jaundice, kernicterus, and hemolytic anemia; avoid use. |
Clinical note
Comprehensive clinical and safety monograph for CHABELINA FE (CHABELINA FE).
| Placental transfer | Yes, crosses placenta; evidence from animal studies and limited human data. |
| Breastfeeding | Unknown if excreted in human milk; potential for serious adverse reactions in nursing infants. Decision to discontinue nursing or drug based on importance to mother. |
| Lactation Rating | L4 |
| Teratogenic Risk | CHABELINA FE contains carbonyl iron, folic acid, and other vitamins/minerals. Carbonyl iron is not associated with increased risk of major malformations. Folic acid is recommended to prevent neural tube defects. No known teratogenic risk in any trimester. |
| Fetal Monitoring | Hemoglobin and hematocrit levels, serum ferritin, reticulocyte count, and complete blood count (CBC) periodically. If overdose occurs, monitor for iron toxicity. |
| Fertility Effects | No known adverse effects on fertility. Iron deficiency may impair fertility; supplementation may improve fertility in iron-deficient women. |
■ FDA Black Box Warning
Estrogen Plus Progestin Therapy: Estrogens plus progestin therapy should not be used for the prevention of cardiovascular disease or dementia. Increased risks of myocardial infarction, stroke, invasive breast cancer, pulmonary emboli, and deep vein thrombosis were reported in postmenopausal women (50-79 years of age) during 5.6 years of treatment with oral conjugated estrogens plus medroxyprogesterone acetate relative to placebo. The Women's Health Initiative (WHI) estrogen plus progestin substudy reported increased risks of invasive breast cancer and coronary heart disease. Other doses of conjugated estrogens with medroxyprogesterone acetate, and other combinations of estrogens and progestins were not studied in the WHI and, in the absence of comparable data, these risks should be assumed to be similar.
| Serious Effects |
Hypersensitivity to any componentSevere hepatic impairmentPregnancy (category unknown, risk of fetal harm)
| Precautions | Cardiovascular disorders: Increased risk of stroke, DVT, pulmonary embolism, and myocardial infarction. Discontinue if thrombotic events occur or are suspected., Malignant neoplasms: Increased risk of endometrial cancer with unopposed estrogen; bazedoxifene reduces but does not eliminate this risk. Increased risk of ovarian cancer. May increase risk of breast cancer; discontinue if breast cancer is detected., Gallbladder disease: Increased risk requiring cholecystectomy., Hypertriglyceridemia: May cause pancreatitis in patients with elevated triglycerides., Hepatic impairment: Use caution; may be contraindicated in severe hepatic disease., Hypothyroidism: May increase thyroid-binding globulin, requiring increased thyroid hormone dose., Fluid retention: Caution in patients with cardiac or renal impairment., Hypocalcemia: May occur in patients with hypoparathyroidism., Hereditary angioedema: Estrogens may exacerbate symptoms., Porphyria: May exacerbate., Osteoporosis: Use only for prevention, not treatment., Dementia: Increased risk of probable dementia in women ≥65 years., Laboratory tests: Monitor thyroid function, triglycerides, and endometrial status as indicated. |
| Food/Dietary | No specific food interactions with hormonal components. Grapefruit juice may increase estrogen exposure; limit consumption. Iron in placebo pills may be less absorbed with coffee, tea, or dairy; take with vitamin C source enhances absorption. No other dietary restrictions. |
| Clinical Pearls | CHABELINA FE is a combination oral contraceptive containing ethinyl estradiol and drospirenone. It also includes ferrous fumarate (iron supplement) in the placebo pills to reduce iron deficiency anemia risk. Drospirenone has anti-mineralocorticoid activity, which may cause hyperkalemia; caution with medications that increase potassium (e.g., ACE inhibitors, NSAIDs). Monitor for thrombotic events; contracepted in women with hypertension >160/100 mmHg or migraine with aura. Absorption of drospirenone may be reduced with hepatic impairment. |
| Patient Advice | Take one pill daily at the same time; missing pills increases pregnancy risk. · Use backup contraception if starting late or missing pills per package instructions. · Report symptoms of blood clots: leg pain/swelling, chest pain, sudden headache, vision changes. · Avoid smoking; smoking increases risk of serious cardiovascular side effects. · Iron in placebo pills may cause dark stools; this is harmless. · Inform your doctor about all medications, especially those affecting potassium levels. |
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