Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
OVULEN 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
Ovulen is a combination oral contraceptive containing ethynodiol diacetate (a progestin) and mestranol (an estrogen). It inhibits ovulation by suppressing gonadotropin-releasing hormone (Gn RH) from the hypothalamus, reducing luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion from the pituitary. It also increases cervical mucus viscosity and alters endometrial development, impeding sperm penetration and implantation.
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 (FDA-approved indication)
Prevention of pregnancy
1 tablet (1 mg ethynodiol diacetate, 50 mcg mestranol) orally once daily for 21 days, followed by 7 days of placebo or no medication.
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.
Ethinylestradiol: 10-20 hours (mean 17 hours); Dimethisterone: 10-15 hours. Clinical context: Steady state achieved after 3-5 days; elimination prolonged in hepatic impairment.
Norethindrone: 8-11 hours (terminal); ethinyl estradiol: 10-20 hours (terminal). The half-life supports once-daily dosing for oral contraceptive efficacy.
Ethynodiol diacetate is rapidly metabolized to norethindrone, primarily via hydrolysis, then undergoes reduction, hydroxylation, and conjugation. Mestranol is metabolized to ethinyl estradiol via demethylation, followed by further hydroxylation and conjugation. Both are metabolized by cytochrome P450 enzymes, including CYP3A4.
Ethinyl estradiol: primarily hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Renal: 50-60% as metabolites (glucuronide and sulfate conjugates), biliary/fecal: 40-50% (enterohepatic circulation).
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%).
Ethinylestradiol: 97-98% bound to albumin and sex hormone-binding globulin (SHBG); Dimethisterone: ~90% bound to albumin and SHBG.
Norethindrone: 61% bound to albumin and SHBG; ethinyl estradiol: 97-98% bound to albumin.
Ethinylestradiol: 2-4 L/kg (large Vd indicating extensive tissue distribution, including reproductive tissues and fat); Dimethisterone: 1.5-2.5 L/kg.
Norethindrone: 3.8-4.5 L/kg; ethinyl estradiol: 2.0-4.0 L/kg. Large Vd indicates extensive tissue distribution.
Oral: Ethinylestradiol 40-60% (first-pass metabolism); Dimethisterone ~70% (oral bioavailability).
Oral: Norethindrone ~64%, ethinyl estradiol ~38-48% (due to first-pass metabolism).
No specific dose adjustment guidelines available; use caution in severe renal impairment (Cr Cl <30 m L/min) due to potential hormonal accumulation.
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 impairment (Child-Pugh class C). In mild to moderate impairment (Child-Pugh A or B), use with caution; no specific dose reduction established.
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.
Approved only for postmenarchal adolescents; same dosing as adults (1 tablet daily for 21 days with 7-day break). Not indicated before menarche.
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. Efficacy and safety in elderly (age >65 years) have not been established.
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 the risk of serious cardiovascular events from combination oral contraceptive use. The risk increases with age, especially in women over 35 years, and with the number of cigarettes smoked. Women who use combination oral contraceptives 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.
Cigarette smoking increases risk of cardiovascular events; avoid in women over 35 who smoke.,Increased risk of thromboembolic disorders (e.g., deep vein thrombosis, pulmonary embolism, stroke, myocardial infarction). Discontinue if thrombotic events occur or are suspected.,Elevated blood pressure; monitor regularly.,Gallbladder disease; may worsen or precipitate.,Hepatic neoplasia; rare cases of benign and malignant liver tumors reported.,Carcinoma of breast and reproductive organs; increased risk with long-term use; monitor if history.,Ocular lesions; discontinue if sudden partial or complete loss of vision, proptosis, diplopia, or papilledema occurs.,Glucose intolerance; use with caution in diabetics.,Unscheduled bleeding; rule out pregnancy or other causes.,Depression; discontinue if severe or recurrent.
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 (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.,Pregnancy (known or suspected).,Benign or malignant liver tumor (current or history).,Jaundice or liver disease (acute or chronic) with abnormal liver function, unless improving.,Hypersensitivity to any component.
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. Grapefruit juice may alter estrogen metabolism but clinical relevance is minimal. Maintain regular diet; no restrictions.
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. Contraindicated in pregnancy due to risk of fetal harm, including cardiovascular anomalies and limb defects. First trimester exposure associated with major congenital malformations; second and third trimester exposure may cause feminization of male 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 human milk; M/P ratio not established. May reduce milk production and affect infant hormonal development. Contraindicated during breastfeeding.
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.
Not applicable; contraindicated in pregnancy. No dose adjustments recommended as medication should be discontinued immediately if pregnancy occurs.
Contraindicated in pregnancy; no dose adjustments applicable. Discontinue medication immediately upon pregnancy detection.
Ovulen (ethynodiol diacetate 1 mg + mestranol 0.1 mg) is a first-generation combined oral contraceptive. Monitor for thromboembolic events, especially in smokers over 35. Use with caution in patients with hypertension, migraine with aura, or liver disease. Breakthrough bleeding is common in the first 3 cycles.
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, even if no sexual activity.,Use backup contraception (e.g., condoms) for the first 7 days of starting the pill.,Report sudden severe headache, chest pain, leg swelling, or vision changes immediately.,Smoking increases risk of serious cardiovascular side effects; avoid smoking.,Missed pills increase pregnancy risk; follow missed pill instructions in the patient leaflet.
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 OVULEN vs ALYACEN 1/35, answered by our medical review team.
OVULEN is a Oral Contraceptive that works by Ovulen is a combination oral contraceptive containing ethynodiol diacetate (a progestin) and mestranol (an estrogen). It inhibits ovulation by suppressing gonadotropin-releasing hormone (Gn RH) from the hypothalamus, reducing luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion from the pituitary. It also increases cervical mucus viscosity and alters endometrial development, impeding sperm penetration and implantation.. 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 OVULEN 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 OVULEN is: 1 tablet (1 mg ethynodiol diacetate, 50 mcg mestranol) orally once daily for 21 days, followed by 7 days of placebo or no medication.. 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 OVULEN 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. OVULEN is classified as Category C. FDA Pregnancy Category X. Contraindicated in pregnancy due to risk of fetal harm, including cardiovascular anomalies and limb defects. First trimester exposure associated with majo. 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.