Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ENOVID-E 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 estrogen-progestin contraceptive. Suppresses gonadotropin release, inhibits ovulation, increases cervical mucus viscosity, and alters endometrial morphology.
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,Dysfunctional uterine bleeding,Endometriosis
Prevention of pregnancy
5 mg orally once daily for 20 days starting on day 5 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.
Norethynodrel: 5-10 hours; mestranol: 2-5 hours (metabolized to ethinyl estradiol, half-life 10-20 hours). Steady-state reached in 5-7 days.
Norethindrone: 8-11 hours (terminal); ethinyl estradiol: 10-20 hours (terminal). The half-life supports once-daily dosing for oral contraceptive efficacy.
Metabolized via hepatic cytochrome P450 enzymes (CYP3A4) and conjugated with glucuronic acid and sulfate. Enterohepatic recirculation occurs.
Ethinyl estradiol: primarily hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Renal (50-60% as metabolites, <1% unchanged); fecal (40-50%)
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%).
Norethynodrel: 95-98% (albumin); mestranol: 97-99% (albumin and SHBG)
Norethindrone: 61% bound to albumin and SHBG; ethinyl estradiol: 97-98% bound to albumin.
Norethynodrel: 2-4 L/kg; mestranol: 3-5 L/kg; 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: >90% for norethynodrel; mestranol: 40-60% (first-pass metabolism)
Oral: Norethindrone ~64%, ethinyl estradiol ~38-48% (due to first-pass metabolism).
No specific guidelines; use with caution in severe renal impairment (GFR <30 m L/min) due to potential fluid retention
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); dose reduction recommended in moderate impairment (Child-Pugh class B: use lowest effective dose)
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 approved for use in pediatric patients; safety and efficacy 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.
No specific dose adjustment; caution due to increased risk of thromboembolic events and fluid retention in elderly patients
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. Use contraindicated in women over 35 years who 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.
Increased risk of thromboembolic disorders, myocardial infarction, stroke, hepatic neoplasia, gallbladder disease, hypertension, and carbohydrate intolerance. Discontinue if jaundice, visual disturbances, or migraine occurs. Monitor blood pressure and liver function.
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, cerebrovascular or coronary artery disease, known or suspected breast carcinoma, endometrial carcinoma, undiagnosed abnormal genital bleeding, known or suspected pregnancy, hepatic adenoma or carcinoma, impaired liver function, and smokers over 35 years.
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 significant food interactions reported. Grapefruit juice may mildly increase estrogen levels but not clinically relevant. Maintain consistent dietary intake to avoid gastrointestinal upset.
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: Increased risk of neural tube defects, congenital heart defects, and limb reduction defects due to progestin and estrogen components. Second and third trimesters: Potential for feminization of male fetus, urogenital abnormalities, and possible long-term neurodevelopmental effects. Use contraindicated in pregnancy.
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; M/P ratio not well established. Potential for adverse effects on infant including jaundice and breast enlargement. Avoid use during breastfeeding due to hormonal effects.
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.
Contraindicated in pregnancy; do not use. No dosing adjustments applicable as use is avoided. If exposure occurs, discontinue immediately and manage supportively.
Contraindicated in pregnancy; no dose adjustments applicable. Discontinue medication immediately upon pregnancy detection.
Enovid-E (5 mg norethynodrel, 0.075 mg mestranol) is a first-generation combined oral contraceptive. Due to high estrogen dose, increased risk of thromboembolism; avoid in smokers over 35 and those with migraine with aura. Typically prescribed for contraception or menstrual disorders. Monitor for breakthrough bleeding and hypertension.
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 tablet daily at the same time for 21 days, then 7 days off.,Do not smoke while taking this medication, especially if over 35.,Watch for signs of blood clots: sudden leg swelling, chest pain, shortness of breath.,Use backup contraception if you miss a pill, especially during the first week.,This medication does not protect against HIV or other sexually transmitted infections.
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 ENOVID-E vs ALYACEN 1/35, answered by our medical review team.
ENOVID-E is a Oral Contraceptive that works by Combination estrogen-progestin contraceptive. Suppresses gonadotropin release, inhibits ovulation, increases cervical mucus viscosity, and alters endometrial morphology.. 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 ENOVID-E 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 ENOVID-E is: 5 mg orally once daily for 20 days starting on day 5 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 ENOVID-E 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. ENOVID-E is classified as Category C. First trimester: Increased risk of neural tube defects, congenital heart defects, and limb reduction defects due to progestin and estrogen components. Second and third trimesters: . 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.