Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
LESSINA-28 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
Combination of a progestin (levonorgestrel) and an estrogen (ethinyl estradiol). Inhibits ovulation by suppressing gonadotropin release; increases cervical mucus viscosity to impede sperm penetration, and induces endometrial changes that reduce implantation likelihood.
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.
Prevention of pregnancy
Prevention of pregnancy
One tablet (0.1 mg levonorgestrel and 0.02 mg ethinyl estradiol) orally once daily for 28 days, starting on the first day of menstrual cycle.
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: 18-22 hours; clinically relevant for 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.
Levonorgestrel: primarily CYP3A4, with reduction and conjugation to sulfate and glucuronide metabolites. Ethinyl estradiol: primarily CYP3A4, undergoes hydroxylation and conjugation to sulfate and glucuronides.
Ethinyl estradiol: primarily hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Renal: 30% as unchanged drug and metabolites; biliary/fecal: 70% as metabolites.
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: 97-99% bound to albumin and SHBG; 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: 2.3 L/kg; indicates 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: approximately 90% for levonorgestrel; approximately 45% for ethinyl estradiol (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. Use caution in severe renal impairment (Cr Cl <30 m L/min) due to potential for fluid retention; consider alternative contraception.
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 acute liver disease or severe cirrhosis (Child-Pugh class B or C). For mild hepatic impairment (Child-Pugh class A), no dose adjustment; 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 before menarche. For post-menarcheal adolescents, same dosing as adults (one tablet daily) with monitoring for bone mineral density and thrombotic risk.
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 after menopause. In perimenopausal women, same dosing as adults; discontinue at menopause due to increased risk of thrombosis and cardiovascular events.
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 from combination oral contraceptives (COCs). Risk increases with age and number of cigarettes smoked (especially in women >35 years). Women who use COCs should be strongly advised not to smoke.
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.
Smoking and cardiovascular risk,Increased risk of thromboembolic events (venous and arterial),Hepatic neoplasia,Gallbladder disease,Hypertension,Carbohydrate and lipid metabolic effects,Headache exacerbation,Bleeding irregularities,Pregnancy and hepatic enzyme induction,Ocular lesions (eg, retinal thrombosis)
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
Thrombophlebitis or thromboembolic disorders,History of deep vein thrombosis or pulmonary embolism,Cerebrovascular or coronary artery disease,Current or history of breast cancer or other estrogen/progestin-sensitive neoplasia,Hepatic adenoma or carcinoma,Undiagnosed abnormal genital bleeding,Known or suspected pregnancy,Active liver disease or impaired liver function,Hypersensitivity to any component,Use with hepatitis C drug combinations containing ombitasvir/paritaprevir/ritonavir with or without dasabuvir
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 dietary restrictions. Grapefruit juice may increase estrogen levels; avoid large quantities. Maintain a consistent intake of caffeine as it can be metabolized more slowly, possibly causing jitteriness.
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.
First trimester: No increased risk of major birth defects based on large cohort studies. Second and third trimesters: Associated with increased risk of intrauterine growth restriction (IUGR), preterm birth, and transient neonatal hepatotoxicity (elevated liver enzymes) with prolonged use.
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).
Minimal excretion into breast milk; M/P ratio approx 0.1–0.3. Considered compatible with breastfeeding by AAP; monitor infant for diarrhea or rash.
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 required; pharmacokinetics unchanged in pregnancy. Use caution in cholestasis or hepatic impairment.
Contraindicated in pregnancy; no dose adjustments applicable. Discontinue medication immediately upon pregnancy detection.
Lessina-28 is a combined oral contraceptive containing ethinyl estradiol and levonorgestrel. Administer at the same time daily to maintain consistent hormone levels and maximize contraceptive efficacy. Use of additional non-hormonal contraception is recommended during the first 7 days of therapy. Missed pills increase breakthrough bleeding and pregnancy risk; consult package insert for missed dose instructions. Drug interactions with rifampin, certain anticonvulsants (e.g., phenytoin, carbamazepine), and St. John's wort may reduce contraceptive effectiveness.
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; if you miss a pill, follow the instructions in the package insert.,Lessina-28 does not protect against HIV or other sexually transmitted infections; use condoms for STI prevention.,Common side effects include nausea, headache, breast tenderness, and breakthrough bleeding; these often improve after a few cycles.,Report severe headaches, vision changes, leg pain or swelling, chest pain, or jaundice to your healthcare provider immediately.,Do not smoke while using this medication; smoking increases risk of serious cardiovascular events, especially in women over 35.
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 LESSINA-28 vs ALYACEN 1/35, answered by our medical review team.
LESSINA-28 is a Oral Contraceptive that works by Combination of a progestin (levonorgestrel) and an estrogen (ethinyl estradiol). Inhibits ovulation by suppressing gonadotropin release; increases cervical mucus viscosity to impede sperm penetration, and induces endometrial changes that reduce implantation likelihood.. 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 LESSINA-28 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 LESSINA-28 is: One tablet (0.1 mg levonorgestrel and 0.02 mg ethinyl estradiol) orally once daily for 28 days, starting on the first day of menstrual cycle.. 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 LESSINA-28 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. LESSINA-28 is classified as Category C. First trimester: No increased risk of major birth defects based on large cohort studies. Second and third trimesters: Associated with increased risk of intrauterine growth restrict. 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.