Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CHABELINA FE vs ALYACEN 1/35
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 hormonal contraceptive: ethinyl estradiol suppresses gonadotropin release via negative feedback on hypothalamic-pituitary axis; norethindrone induces progestational effects including cervical mucus thickening and endometrial changes, inhibiting ovulation and sperm penetration.
Moderate to severe vasomotor symptoms due to menopause,Prevention of postmenopausal osteoporosis
Prevention of pregnancy
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.
One tablet (norethindrone 1 mg and ethinyl estradiol 35 mcg) orally once daily for 21 consecutive days, followed by 7 days of placebo or no tablets.
Terminal elimination half-life: 8-12 hours; clinically relevant for dosing interval in moderate renal impairment
Norethindrone: 8-11 hours (terminal); ethinyl estradiol: 10-20 hours (terminal). The half-life supports once-daily dosing for oral contraceptive efficacy.
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 hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Primarily renal; 40-60% excreted unchanged in urine; biliary/fecal elimination accounts for <5%
Renal excretion of metabolites (primarily ethinyl estradiol and norethindrone conjugates) accounts for approximately 50-60% of elimination; fecal excretion accounts for 30-40%. Unchanged drug excretion is minimal (<5%).
~70-80% bound to serum albumin and alpha-1 acid glycoprotein
Norethindrone: 61% bound to albumin and SHBG; ethinyl estradiol: 97-98% bound to albumin.
2-3 L/kg; indicates extensive tissue distribution, including passage into CSF
Norethindrone: 3.8-4.5 L/kg; ethinyl estradiol: 2.0-4.0 L/kg. Large Vd indicates extensive tissue distribution.
Oral: 95-100%
Oral: Norethindrone ~64%, ethinyl estradiol ~38-48% (due to first-pass 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 impairment or acute renal failure due to potential fluid retention and electrolyte disturbances.
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 patients with hepatic impairment, including Child-Pugh class B or C, due to impaired metabolism of estrogen and progestin. Not recommended in patients with active liver disease or history of liver tumors.
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. Safety and efficacy established for contraception; weight-based dosing not applicable.
Not indicated for postmenopausal women; no specific dose adjustment recommended for elderly patients with normal hepatic and renal function.
Not indicated for use after menopause due to lack of benefit and increased risks (e.g., cardiovascular, thromboembolic events). If used, monitor for fluid retention, hypertension, and glucose intolerance.
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 and heavy smoking (≥15 cigarettes/day). Women over 35 who smoke should not use this product.
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 (e.g., DVT, PE, stroke, MI),Cerebrovascular disease,Hepatic neoplasia,Gallbladder disease,Hypertension,Carbohydrate and lipid effects,Ocular lesions,Hereditary angioedema,Chloasma,Menstrual irregularities,Pregnancy exclusion prior to initiation
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
Venous or arterial thrombotic/thromboembolic disease (current or history),Cerebrovascular disease,Coronary artery disease,Known or suspected breast cancer,Endometrial or other estrogen-dependent neoplasia,Undiagnosed abnormal genital bleeding,Cholestatic jaundice of pregnancy or jaundice with prior pill use,Hepatic adenoma or carcinoma,Known or suspected pregnancy,Hypersensitivity to any component,Smoking in women over 35
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. Grapefruit juice may increase estrogen levels, but clinically not a concern. Avoid excessive alcohol, which may impair liver function and increase estrogen exposure. Maintain a healthy diet, as weight gain is possible.
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.
Pregnancy category X. Use of ALYACEN 1/35 (norethindrone/ethinyl estradiol) is contraindicated during pregnancy. First trimester: Increased risk of congenital anomalies, including cardiovascular defects and limb reduction defects. Second/third trimesters: Potential for urogenital abnormalities and feminization of male fetus. Exposure is associated with subsequent development of clear cell adenocarcinoma of vagina/cervix in female offspring (DES-related).
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.
Small amounts of contraceptive steroids and/or metabolites have been identified in breast milk. M/P ratio: Not specifically determined for this combination; ethinyl estradiol M/P ratio ~0.02-0.04. Use may reduce milk production and quality. Breastfeeding not recommended during use. Alternative contraception advised.
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 adjustments applicable. Discontinue medication immediately upon pregnancy detection.
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.
ALYACEN 1/35 is a combination oral contraceptive containing ethinyl estradiol 35 mcg and norgestimate 1 mg. It is indicated for the prevention of pregnancy and for the treatment of moderate acne vulgaris in females ≥15 years of age who desire an oral contraceptive. Monitor for thromboembolic events, especially in smokers over 35 or those with migraine with aura. Use with caution in patients with liver impairment or history of cholestatic jaundice. The pill-free interval should not exceed 7 days; missed pills increase ovulation risk. Consider non-hormonal backup if vomiting or diarrhea occurs within 4 hours of dosing.
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; do not skip doses.,Use an additional non-hormonal contraceptive (e.g., condoms) if you miss a pill, have vomiting, or diarrhea.,Smoking while on this pill increases the risk of blood clots and stroke, especially if you are over 35.,Contact your healthcare provider immediately if you have chest pain, leg pain/swelling, sudden vision changes, or severe headache.,This medication does not protect against HIV or other sexually transmitted infections.,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 ALYACEN 1/35, 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.. ALYACEN 1/35 is a Oral Contraceptive that works by Combination hormonal contraceptive: ethinyl estradiol suppresses gonadotropin release via negative feedback on hypothalamic-pituitary axis; norethindrone induces progestational effects including cervical mucus thickening and endometrial changes, inhibiting ovulation and sperm penetration.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CHABELINA FE and ALYACEN 1/35 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 ALYACEN 1/35 is: One tablet (norethindrone 1 mg and ethinyl estradiol 35 mcg) orally once daily for 21 consecutive days, followed by 7 days of placebo or no tablets.. 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 ALYACEN 1/35 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 . ALYACEN 1/35 is classified as Category C. Pregnancy category X. Use of ALYACEN 1/35 (norethindrone/ethinyl estradiol) is contraindicated during pregnancy. First trimester: Increased risk of congenital anomalies, including . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.