Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
N.E.E. 1/35 21 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 estrogen-progestin contraceptive: ethinyl estradiol (estrogen) and norethindrone (progestin). Suppresses gonadotropin (FSH, LH) release via negative feedback, inhibiting ovulation; increases cervical mucus viscosity to impede sperm penetration; alters endometrial development to reduce implantation likelihood.
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 (FDA-approved)
Prevention of pregnancy,Treatment of moderate acne vulgaris (in females ≥15 years with no contraindications)
One tablet orally once daily for 21 days, followed by 7 days off.
1 tablet (ethinyl estradiol 0.03 mg / levonorgestrel 0.15 mg) orally once daily for 21 days, followed by 7 placebo days.
Norethindrone: terminal half-life 7-8 hours; Ethinyl estradiol: terminal half-life 12-14 hours (with enterohepatic recycling). Clinically, steady state achieved after 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.
Ethinyl estradiol: primarily hepatic via CYP3A4, undergoes conjugation (glucuronidation and sulfation). Norethindrone: hepatic reduction and conjugation, also metabolized by CYP3A4. Both undergo enterohepatic recirculation.
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 (NET) and ethinyl estradiol (EE) are excreted primarily in urine (~50-60% as metabolites) and feces (~30-40% as metabolites); less than 1% excreted unchanged.
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: ~98% bound (albumin).
Levonorgestrel: 98-99% bound to sex hormone-binding globulin (SHBG) and albumin; ethinyl estradiol: 98% bound to albumin.
Norethindrone: Vd 4-5 L/kg; Ethinyl estradiol: Vd 3-4 L/kg; indicates extensive tissue distribution.
Levonorgestrel: Vd ~1.8 L/kg (suggesting extensive tissue distribution). Ethinyl estradiol: Vd ~2.4 L/kg.
Oral: Norethindrone ~64%; Ethinyl estradiol ~45% (first-pass metabolism).
Oral bioavailability: levonorgestrel ~100% (nearly complete); ethinyl estradiol ~45-50% (first-pass hepatic metabolism).
No dose adjustment required. Use with caution in severe impairment.
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 B or C (moderate to severe hepatic impairment).
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 prepubertal children; use only after menarche per adult dosing.
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 contraception postmenopausal; use lowest effective dose for hormone therapy if applicable.
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 from combination oral contraceptive use. Risk increases with age (especially >35 years) and with heavy smoking (>15 cigarettes/day). Women over 35 who smoke should not use this product.
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.
Increased risk of thromboembolic disorders (e.g., DVT, PE, stroke, MI),Cigarette smoking significantly increases cardiovascular risk (see boxed warning),Elevated blood pressure,Hepatic neoplasia (benign and malignant) reported with long-term use,Gallbladder disease,Carbohydrate and lipid metabolic effects (monitor in prediabetic/diabetic patients),Headache (including migraine), discontinue if new or worsening pattern,Bleeding irregularities (breakthrough bleeding, amenorrhea),Chloasma (may persist after discontinuation),Retinal thrombosis (discontinue if unexplained vision loss)
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),Cerebrovascular or coronary artery disease (current or history),Known or suspected pregnancy,Undiagnosed abnormal genital bleeding,Known or suspected breast cancer (current or history),Estrogen-dependent neoplasia (current or history),Hepatic adenoma or carcinoma (current or history),Active liver disease or impaired hepatic function (including jaundice with prior pill use),Major surgery with prolonged immobilization,Hypersensitivity to any component of the product,Age >35 years and smoking
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
Avoid grapefruit and grapefruit juice during treatment due to potential increase in estrogen exposure and risk of adverse effects. No other significant food interactions reported.
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.
N. E. E. 1/35 21 (norethindrone/ethinyl estradiol) is contraindicated in pregnancy. First trimester: No increased risk of major birth defects based on population data, but should not be used once pregnancy is confirmed. Second and third trimesters: Known risks include feminization of male fetus, cardiovascular and skeletal abnormalities, and potential for long-term effects on the child. Immediate discontinuation if pregnancy occurs.
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.
Contraindicated in breastfeeding. Estrogen and progestins pass into breast milk; may reduce milk quantity and quality. Estrogen can suppress lactation. M/P ratio for norethindrone is approximately 0.5–1.0; for ethinyl estradiol, M/P ratio is about 0.2. Use postpartum only after breastfeeding is fully established and only if no alternative. Generally avoid.
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.
No dosing adjustments applicable as drug is contraindicated in pregnancy. If inadvertently used, discontinue immediately. Pharmacokinetic changes in pregnancy (increased clearance, volume of distribution) are not relevant due to contraindication.
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.
N. E. E. 1/35 21 is a monophasic combined oral contraceptive containing 1 mg norethindrone and 35 mcg ethinyl estradiol. It can be used for cycle control and dysmenorrhea. Missed pill management: if one pill is missed, take it as soon as remembered; if two or more are missed, use backup contraception for 7 days. Consider potential drug interactions with rifampin, certain anticonvulsants, and St. John's Wort which may reduce efficacy.
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 each day for 21 days, then 7 days off.,If you miss a pill, take it as soon as you remember. If more than one pill is missed, use backup contraception.,This medication does not protect against sexually transmitted infections.,Common side effects include nausea, headache, breast tenderness, and breakthrough bleeding.,Smoking increases risk of serious cardiovascular side effects; avoid smoking, especially if over 35.,Report symptoms of blood clots such as leg pain/swelling, chest pain, or sudden shortness of breath.
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 N.E.E. 1/35 21 vs ALTAVERA, answered by our medical review team.
N.E.E. 1/35 21 is a Oral Contraceptive that works by Combination estrogen-progestin contraceptive: ethinyl estradiol (estrogen) and norethindrone (progestin). Suppresses gonadotropin (FSH, LH) release via negative feedback, inhibiting ovulation; increases cervical mucus viscosity to impede sperm penetration; alters endometrial development to reduce implantation likelihood.. 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 N.E.E. 1/35 21 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 N.E.E. 1/35 21 is: One tablet orally once daily for 21 days, followed by 7 days off.. 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 N.E.E. 1/35 21 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. N.E.E. 1/35 21 is classified as Category C. N.E.E. 1/35 21 (norethindrone/ethinyl estradiol) is contraindicated in pregnancy. First trimester: No increased risk of major birth defects based on population data, but should not. 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.