Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
LEVLITE 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
Levonorgestrel is a progestin that suppresses ovulation by inhibiting gonadotropin release (LH and FSH) and alters cervical mucus, endometrial thickness, and tubal motility.
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.
Emergency contraception,Contraception (as part of combination oral contraceptives or intrauterine system),Off-label: menstrual disorders, endometriosis
Prevention of pregnancy
One tablet (levonorgestrel 0.1 mg, ethinyl estradiol 0.02 mg) orally once daily for 21 days, followed by 7 placebo tablets.
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: 21-28 hours; clinical context: permits once-daily dosing
Norethindrone: 8-11 hours (terminal); ethinyl estradiol: 10-20 hours (terminal). The half-life supports once-daily dosing for oral contraceptive efficacy.
Hepatic via CYP3A4; reduced to inactive metabolites; excreted in urine and feces.
Ethinyl estradiol: primarily hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Renal: ~50% (30% as unchanged drug, 20% as metabolites); Fecal: ~40%; Biliary: minor
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%).
Levonorgestrel: ~99% bound to sex hormone-binding globulin (SHBG) and albumin; Ethinyl estradiol: ~98% bound to albumin
Norethindrone: 61% bound to albumin and SHBG; ethinyl estradiol: 97-98% bound to albumin.
Levonorgestrel: 1.8 L/kg; Ethinyl estradiol: 2.5 L/kg; clinical meaning: extensive tissue distribution
Norethindrone: 3.8-4.5 L/kg; ethinyl estradiol: 2.0-4.0 L/kg. Large Vd indicates extensive tissue distribution.
Oral: ~100% for both levonorgestrel and ethinyl estradiol (high bioavailability due to minimal first-pass metabolism)
Oral: Norethindrone ~64%, ethinyl estradiol ~38-48% (due to first-pass metabolism).
No dose adjustment required for mild to moderate renal impairment. Not studied in severe renal impairment (GFR <30 m L/min); use with caution.
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 severe hepatic disease (Child-Pugh Class C). For mild to moderate impairment (Child-Pugh A/B), use with caution and monitor liver function.
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.
Not indicated for use in postmenarchal pediatric patients; safety and efficacy not established in prepubertal children.
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 use in postmenopausal women; no specific geriatric dosing studies available.
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.
Cigarette smoking increases risk of serious cardiovascular events. Women over 35 who smoke should not use combination hormonal contraceptives.
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.
Thrombotic disorders,Hepatic disease,Hypertension,Diabetes,Gallbladder disease,Depression,Ectopic pregnancy risk (emergency contraception),Reduced efficacy with CYP3A4 inducers
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
Known or suspected pregnancy,Undiagnosed abnormal genital bleeding,Severe hepatic disease,Known or suspected breast cancer,History of thromboembolic disorders,Hypersensitivity to levonorgestrel
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 known significant food interactions. Grapefruit and grapefruit juice do not interact with ethinyl estradiol or levonorgestrel. However, a high-fat meal may increase absorption of some oral contraceptives; consistency in taking with or without food is recommended.
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.
FDA Pregnancy Category X. Ethinyl estradiol and levonorgestrel are contraindicated in pregnancy due to risk of fetal harm, including cardiovascular defects and limb reduction defects from first-trimester exposure. Second and third trimester exposure may be associated with genitourinary abnormalities and masculinization of female fetuses.
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).
Excreted in breast milk in small amounts. Ethinyl estradiol concentration in milk ~0.02-0.1 ng/m L; levonorgestrel M/P ratio ~0.35-1.0. No adverse effects reported at typical doses. May reduce milk production; use caution in lactating women, especially with high doses.
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.
No dose adjustment applicable as use is contraindicated in pregnancy. Pharmacokinetic changes in pregnancy (increased clearance, decreased binding protein) are irrelevant due to contraindication.
Contraindicated in pregnancy; no dose adjustments applicable. Discontinue medication immediately upon pregnancy detection.
LEVLITE is a combination oral contraceptive containing ethinyl estradiol and levonorgestrel. Use with caution in women with migraines with aura due to increased stroke risk. Smoking increases cardiovascular risk, especially in women over 35. Monitor blood pressure at baseline and periodically. Consider alternative contraception in women with uncontrolled hypertension or history of venous thromboembolism.
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 each day.,If you miss a pill, follow the package instructions or consult your healthcare provider.,Do not smoke while taking this medication, as it increases the risk of blood clots and heart problems.,Use barrier contraception if you also take certain antibiotics or anticonvulsants.,Common side effects include nausea, headache, and breast tenderness, which often improve after a few months.,Seek immediate medical help for symptoms of a blood clot: leg pain/swelling, sudden chest pain, or trouble breathing.
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 LEVLITE vs ALYACEN 1/35, answered by our medical review team.
LEVLITE is a Oral Contraceptive that works by Levonorgestrel is a progestin that suppresses ovulation by inhibiting gonadotropin release (LH and FSH) and alters cervical mucus, endometrial thickness, and tubal motility.. 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 LEVLITE and ALYACEN 1/35 depend on the specific clinical indication. These are both Oral Contraceptive agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of LEVLITE is: One tablet (levonorgestrel 0.1 mg, ethinyl estradiol 0.02 mg) orally once daily for 21 days, followed by 7 placebo tablets.. 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 LEVLITE 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. LEVLITE is classified as Category C. FDA Pregnancy Category X. Ethinyl estradiol and levonorgestrel are contraindicated in pregnancy due to risk of fetal harm, including cardiovascular defects and limb reduction defec. 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.