Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CHABELINA FE vs ALTAVERA
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
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.
Combination of ethinyl estradiol and desogestrel: ethinyl estradiol suppresses gonadotropin release, inhibiting ovulation; desogestrel (progestin) causes cervical mucus thickening and endometrial atrophy, preventing implantation.
Moderate to severe vasomotor symptoms due to menopause,Prevention of postmenopausal osteoporosis
Prevention of pregnancy,Treatment of moderate acne vulgaris (in females ≥15 years with no contraindications)
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.
1 tablet (ethinyl estradiol 0.03 mg / levonorgestrel 0.15 mg) orally once daily for 21 days, followed by 7 placebo days.
Terminal elimination half-life: 8-12 hours; clinically relevant for dosing interval in moderate renal impairment
Levonorgestrel: terminal elimination half-life 25±10 hours; ethinyl estradiol: 13±7 hours. Clinical context: steady-state concentrations achieved within 5-7 days; contraceptive efficacy requires consistent daily dosing.
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.
Ethinyl estradiol: primarily metabolized by CYP3A4; undergoes sulfation and glucuronidation. Desogestrel: rapidly converted to active metabolite etonogestrel via CYP2C9 and CYP2C19; further metabolism by CYP3A4.
Primarily renal; 40-60% excreted unchanged in urine; biliary/fecal elimination accounts for <5%
Renal excretion of metabolites and unchanged drug: ~30% (levonorgestrel) and ~20% (ethinyl estradiol) in urine; biliary/fecal elimination: ~40-50% as conjugates and metabolites.
~70-80% bound to serum albumin and alpha-1 acid glycoprotein
Levonorgestrel: 98-99% bound to sex hormone-binding globulin (SHBG) and albumin; ethinyl estradiol: 98% bound to albumin.
2-3 L/kg; indicates extensive tissue distribution, including passage into CSF
Levonorgestrel: Vd ~1.8 L/kg (suggesting extensive tissue distribution). Ethinyl estradiol: Vd ~2.4 L/kg.
Oral: 95-100%
Oral bioavailability: levonorgestrel ~100% (nearly complete); ethinyl estradiol ~45-50% (first-pass hepatic metabolism).
Contraindicated in GFR < 30 m L/min/1.73 m²; no adjustment needed for GFR ≥ 30 m L/min/1.73 m².
No dose adjustment required for mild to moderate renal impairment. Contraindicated in severe renal disease or acute renal failure due to potential fluid retention.
Contraindicated in Child-Pugh Class C; use not recommended in Child-Pugh Class A or B due to potential steroid hormone clearance issues.
Contraindicated in severe hepatic dysfunction (Child-Pugh class B or C). Use caution in mild to moderate impairment (Child-Pugh A); monitor liver enzymes.
Post-menarchal adolescents: same as adult dosing; safety and efficacy in pre-menarchal patients not established.
Not indicated for use before menarche. For postmenarchal adolescents, same dosing as adults (1 tablet daily, 21/7 regimen) after evaluation of risks.
Not indicated for postmenopausal women; no specific dose adjustment recommended for elderly patients with normal hepatic and renal function.
Not indicated for postmenopausal women. No specific geriatric dosing; consider increased risk of thromboembolism, cardiovascular disease, and metabolic effects in older women of reproductive age.
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.
Cigarette smoking increases risk of serious cardiovascular events from combined oral contraceptives. Risk increases with age (especially >35 years) and with number of cigarettes smoked. Women who use combined hormonal contraceptives should be strongly advised not to smoke.
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.
Thrombotic disorders: risk of venous thromboembolism (VTE), stroke, myocardial infarction; discontinue if thrombotic event occurs.,Hepatic disease: discontinue if jaundice or liver function abnormalities develop.,Hypertension: monitor blood pressure; discontinue if uncontrolled.,Carbohydrate metabolism: may affect glucose tolerance; monitor diabetic patients.,Depression: discontinue if significant depression occurs.,Gallbladder disease: increased risk of cholelithiasis.
Undiagnosed abnormal genital bleeding,Known, suspected, or history of breast cancer,Known or suspected estrogen-dependent neoplasia (e.g., endometrial cancer),Active or history of venous thromboembolism (DVT, PE),Active or history of arterial thromboembolism (stroke, MI),Known anaphylactic reaction or angioedema to any component,Hepatic impairment or disease,Known protein C, protein S, or antithrombin deficiency or other thrombophilic disorders,Known or suspected pregnancy
Thrombophlebitis or thromboembolic disorders (current or history),Cerebrovascular or coronary artery disease (current or history),Known or suspected breast carcinoma,Estrogen-dependent neoplasia (known or suspected),Undiagnosed abnormal genital bleeding,Cholestatic jaundice of pregnancy or jaundice with prior pill use,Hepatic adenoma or carcinoma (known or suspected),Pregnancy (known or suspected),Hypersensitivity to any component
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.
No significant food interactions. Alcohol does not affect efficacy but may increase risk of adverse effects such as nausea. Grapefruit juice has no known interaction. Avoid excessive alcohol consumption due to potential hepatotoxicity.
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.
ALTAVERA contains ethinyl estradiol and levonorgestrel. First trimester: Inadvertent exposure during organogenesis is associated with a very low absolute risk of cardiovascular defects (relative risk 1.2-1.4) and no consistent increase in other major malformations. Second and third trimesters: No known teratogenic effects, but theoretical risks from estrogenic effects (e.g., feminization of male fetus). Postnatal: No increased risk of long-term developmental effects from pregnancy exposure.
Iron and folic acid are excreted into breast milk in small amounts. Iron supplementation may increase milk iron concentration. No adverse effects reported. M/P ratio not established.
Combined oral contraceptives may reduce milk production and quality, especially in early lactation. Ethinyl estradiol transfers into breast milk at low levels (M/P ratio approximately 0.1-0.2), excluding clinical effects in term infants. Levonorgestrel transfer is minimal (M/P ratio ~0.2-0.4). Use is generally avoided in breastfeeding women, especially during the first 6 weeks postpartum. Progestin-only methods are preferred.
Dose adjustments not typically required. Pregnancy may increase iron requirements; ensure adequate intake. Pharmacokinetic changes (e.g., increased plasma volume) may necessitate higher doses in iron deficiency.
Contraindicated in pregnancy. No dose adjustment recommended because use is discontinued upon confirmed or suspected pregnancy. Pharmacokinetic changes in pregnancy (e.g., increased hepatic clearance, altered binding proteins) are not relevant for this indication.
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 mm Hg or migraine with aura. Absorption of drospirenone may be reduced with hepatic impairment.
ALTAVERA is a combined oral contraceptive (COC) containing ethinylestradiol and levonorgestrel. It inhibits ovulation via suppression of gonadotropins. Counsel patients to take at the same time daily to maintain efficacy. Missed pill management: if missed within 12 hours, take immediately; if >12 hours, take last missed pill and use backup contraception for 7 days. Be aware of increased VTE risk, especially in smokers over 35. May reduce effectiveness of lamotrigine; monitor seizure control. Initiate on the first day of menses or first Sunday after onset.
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.
Take one tablet daily at the same time each day, with or without food.,If you miss a pill by less than 12 hours, take it as soon as you remember. If more than 12 hours, take the missed pill and use a backup method (e.g., condoms) for the next 7 days.,Smoking increases your risk of serious cardiovascular side effects, especially if you are over 35 years old. Do not smoke while taking this medication.,Seek immediate medical attention if you experience sudden severe headache, chest pain, leg pain/swelling, or vision changes (symptoms of blood clots).,This medication does not protect against HIV or other sexually transmitted infections.,If you are taking lamotrigine or other anticonvulsants, tell your doctor; your seizure medication may be less effective.,Store at room temperature away from moisture and heat.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about CHABELINA FE vs ALTAVERA, answered by our medical review team.
CHABELINA FE is a Oral contraceptive that works by 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.. ALTAVERA is a Combined Oral Contraceptive that works by Combination of ethinyl estradiol and desogestrel: ethinyl estradiol suppresses gonadotropin release, inhibiting ovulation; desogestrel (progestin) causes cervical mucus thickening and endometrial atrophy, preventing implantation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CHABELINA FE and ALTAVERA depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of CHABELINA FE is: 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.. The standard adult dose of ALTAVERA is: 1 tablet (ethinyl estradiol 0.03 mg / levonorgestrel 0.15 mg) orally once daily for 21 days, followed by 7 placebo days.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between CHABELINA FE and ALTAVERA in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. CHABELINA FE is classified as Category C. 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 . ALTAVERA is classified as Category C. ALTAVERA contains ethinyl estradiol and levonorgestrel. First trimester: Inadvertent exposure during organogenesis is associated with a very low absolute risk of cardiovascular def. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.