Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
NORLESTRIN FE 1/50 vs ALTAVERA
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Combination of ethinyl estradiol and norethindrone acetate provides negative feedback on gonadotropin release, suppressing ovulation. Also causes cervical mucus thickening and endometrial thinning.
Combination of ethinyl estradiol and desogestrel: ethinyl estradiol suppresses gonadotropin release, inhibiting ovulation; desogestrel (progestin) causes cervical mucus thickening and endometrial atrophy, preventing implantation.
Prevention of pregnancy,Oral contraceptive
Prevention of pregnancy,Treatment of moderate acne vulgaris (in females ≥15 years with no contraindications)
One tablet (norethindrone 1 mg and ethinyl estradiol 50 mcg plus ferrous fumarate 75 mg) orally once daily for 28 days, with 21 active tablets and 7 placebo tablets.
1 tablet (ethinyl estradiol 0.03 mg / levonorgestrel 0.15 mg) orally once daily for 21 days, followed by 7 placebo days.
Norethindrone: 5-12 hours (mean 8 hours). Ethinyl estradiol: 11-16 hours. Clinical context: Steady state reached in 5-7 days.
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.
Norethindrone acetate: extensively metabolized via reduction (to active 5α-dihydro derivatives), hydroxylation, and conjugation; primarily by CYP3A4. Ethinyl estradiol: metabolized by CYP3A4 via hydroxylation and conjugation; undergoes enterohepatic circulation.
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.
Norethindrone: 20% renal, 80% fecal. Ethinyl estradiol: 40% renal, 60% fecal.
Renal excretion of metabolites and unchanged drug: ~30% (levonorgestrel) and ~20% (ethinyl estradiol) in urine; biliary/fecal elimination: ~40-50% as conjugates and metabolites.
Norethindrone: 97% bound (albumin, SHBG). Ethinyl estradiol: 97% bound (albumin, SHBG, CBG).
Levonorgestrel: 98-99% bound to sex hormone-binding globulin (SHBG) and albumin; ethinyl estradiol: 98% bound to albumin.
Norethindrone: 2-4 L/kg; Ethinyl estradiol: 2-4 L/kg; reflects tissue distribution.
Levonorgestrel: Vd ~1.8 L/kg (suggesting extensive tissue distribution). Ethinyl estradiol: Vd ~2.4 L/kg.
Oral: Norethindrone ~64%, Ethinyl estradiol ~38% (first-pass metabolism).
Oral bioavailability: levonorgestrel ~100% (nearly complete); ethinyl estradiol ~45-50% (first-pass hepatic metabolism).
No specific GFR-based dose modifications are recommended. Use with caution in patients with renal impairment or history of renal disease.
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 patients with hepatic impairment (Child-Pugh class A, B, or C) due to reduced clearance and risk of adverse effects.
Contraindicated in severe hepatic dysfunction (Child-Pugh class B or C). Use caution in mild to moderate impairment (Child-Pugh A); monitor liver enzymes.
Not indicated in pediatric patients before menarche. In adolescents, dosing is the same as adults (one tablet daily). Safety and efficacy in post-menarcheal adolescents are similar to adults.
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 in geriatric patients. No specific dose adjustment; however, consider age-related risks (e.g., thromboembolism, cardiovascular disease). Use lowest effective dose if necessary.
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.
Cigarette smoking increases risk of serious cardiovascular events (e.g., stroke, myocardial infarction, thromboembolism) from combined hormonal contraceptive use, especially in women over 35 years who smoke.
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.
Thrombotic disorders (DVT, PE, stroke, MI), hepatic neoplasia, gallbladder disease, carbohydrate/lipid effects, hypertension, hereditary angioedema, chloasma, retinal thrombosis (discontinue if sudden vision loss/proptosis/diplopia), depression.
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.
Thrombophlebitis/venous thromboembolism (current or history), arterial thromboembolic disease (e.g., stroke, MI), cerebrovascular disease, coronary artery disease, valvular heart disease with complications, thrombogenic arrhythmias, diabetes with vascular involvement, severe hypertension, liver tumors or active liver disease, undiagnosed abnormal uterine bleeding, known or suspected pregnancy, breast cancer, hypersensitivity to components, jaundice with prior OC use, heavy smoking (>15 cigarettes/day) in women over 35.
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
Grapefruit juice may increase estrogen levels via CYP3A4 inhibition; avoid large quantities. No specific food restrictions, but high-fat meals may delay absorption. Iron absorption is reduced by calcium-rich foods, tea, and coffee; take iron tablets separately from these.
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.
Category X. Not indicated for use during pregnancy. First trimester: No increased risk of birth defects from inadvertent use; however, use is contraindicated. Second and third trimesters: Androgenic steroid exposure may cause feminization of male fetus, genital abnormalities, and potential long-term effects; no safe use established.
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.
Excreted in breast milk in small amounts. M/P ratio not established. May reduce milk production and quality. Use is not recommended during breastfeeding. Consider alternative contraception.
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.
Contraindicated in pregnancy; no dose adjustment applicable. If pregnancy occurs, discontinue immediately.
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.
Withdrawal bleeding typically occurs during the iron-only tablet phase; absence of bleeding requires pregnancy testing. Iron supplementation in active tablets may cause GI upset. CYP3A4 inducers (e.g., rifampin, carbamazepine) reduce contraceptive efficacy. Venous thromboembolism risk is higher with estrogen-containing pills; avoid in migraine with aura or hypertension.
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 tablet daily at the same time; the last 7 tablets contain iron, not hormones.,Use backup contraception (e.g., condoms) if you miss a pill, vomit within 2 hours, or have severe diarrhea.,This does not protect against STIs; use condoms for prevention.,Report sudden severe headache, chest pain, leg swelling, or vision changes immediately.,Iron tablets may cause constipation or dark stools; this is normal.
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 NORLESTRIN FE 1/50 vs ALTAVERA, answered by our medical review team.
NORLESTRIN FE 1/50 is a Oral Contraceptive that works by Combination of ethinyl estradiol and norethindrone acetate provides negative feedback on gonadotropin release, suppressing ovulation. Also causes cervical mucus thickening and endometrial thinning.. 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 NORLESTRIN FE 1/50 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 NORLESTRIN FE 1/50 is: One tablet (norethindrone 1 mg and ethinyl estradiol 50 mcg plus ferrous fumarate 75 mg) orally once daily for 28 days, with 21 active tablets and 7 placebo tablets.. 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 NORLESTRIN FE 1/50 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. NORLESTRIN FE 1/50 is classified as Category C. Category X. Not indicated for use during pregnancy. First trimester: No increased risk of birth defects from inadvertent use; however, use is contraindicated. Second and third trim. 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.