Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
OGESTREL 0.5/50-21 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 norgestrel and ethinyl estradiol suppresses gonadotropin release, inhibiting ovulation; alters cervical mucus and endometrial lining.
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 (norgestrel 0.5 mg / ethinyl estradiol 0.05 mg) orally once daily for 21 days, followed by 7 placebo days.
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.
Norgestrel: 24-32 hours; Ethinyl estradiol: 7-12 hours. Clinical context: Steady state achieved after 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.
Hepatic, via CYP3A4; norgestrel undergoes reduction, conjugation; ethinyl estradiol is metabolized by CYP3A4 and undergoes glucuronidation.
Ethinyl estradiol: primarily hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Renal: ~50% (metabolites); Fecal/Biliary: ~50% (metabolites); <1% unchanged in urine.
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%).
Norgestrel: 93-95% to albumin and SHBG; Ethinyl estradiol: 97-98% to albumin.
Norethindrone: 61% bound to albumin and SHBG; ethinyl estradiol: 97-98% bound to albumin.
Norgestrel: 2.5-3.5 L/kg; Ethinyl estradiol: 2.5-4 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: Norgestrel ~95%; Ethinyl estradiol ~40-60% due to 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; contraindicated in severe renal disease 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 acute or chronic hepatic disease; do not use in Child-Pugh class B or C. Use with caution in mild impairment (Child-Pugh A) at minimal 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 indicated for use before menarche. For postmenarchal adolescents, same dosing as adults (one tablet daily for 21 days).
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 elderly patients, evaluate cardiovascular and hepatic status; consider lower estrogen dose if necessary.
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; 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 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; hepatic neoplasia; elevated blood pressure; gallbladder disease; carbohydrate and lipid metabolism effects; breakthrough bleeding and spotting; use in pregnancy; depression; contact lens intolerance; fluid retention; hereditary angioedema.
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 carcinoma of the breast; carcinoma of the endometrium or other estrogen-dependent neoplasia; undiagnosed abnormal genital bleeding; pregnancy; jaundice with prior pill use; hepatic adenoma or carcinoma; age >35 and smoking ≥15 cigarettes/day.
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
Grapefruit juice may inhibit CYP3A4 metabolism of ethinyl estradiol, potentially increasing estrogen exposure and risk of adverse effects. Avoid large quantities (e.g., >1 quart/day). No other significant food interactions. St. John's Wort may reduce contraceptive efficacy.
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.
Pregnancy category X. Contraindicated in pregnancy due to known teratogenicity. First trimester: limb defects, cardiac anomalies; second/third trimester: feminization of male fetus, urogenital abnormalities.
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; may reduce milk production and composition. M/P ratio not established. Use not recommended in nursing mothers.
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 adjustments as use is contraindicated during pregnancy.
Contraindicated in pregnancy; no dose adjustments applicable. Discontinue medication immediately upon pregnancy detection.
This combination oral contraceptive (COC) contains 0.5 mg norgestrel (a progestin) and 50 mcg ethinyl estradiol (a high-estrogen dose). It is a monophasic 21-day regimen. Use for contraception; also FDA-approved for moderate acne vulgaris in women >=15 years. High estrogen dose increases thrombotic risk; avoid in smokers over 35, hypertension, migraine with aura, or history of VTE. Advise consistent intake time (daily, same time). Breakthrough bleeding may occur; rule out pregnancy if missed pills. Antiepileptics (e.g., phenytoin, carbamazepine) and rifampin reduce efficacy.
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 for 21 days, then 7 days off; withdrawal bleeding occurs during the 7-day break.,Use backup contraception (e.g., condoms) if you miss a pill, vomit within 2 hours of taking it, or have severe diarrhea.,This pill does not protect against HIV or other sexually transmitted infections.,Serious side effects: leg pain (DVT), chest pain (PE), severe headache (stroke), jaundice (liver disease); stop and call doctor immediately.,Do not smoke while taking this pill, especially if over 35; smoking greatly increases risk of blood clots.,Tell your doctor if you are breastfeeding, planning pregnancy, or have any medical conditions (e.g., hypertension, diabetes, migraine).,Grapefruit juice may increase estrogen levels; avoid excessive consumption.,Antibiotics (e.g., rifampin) and certain anticonvulsants can reduce effectiveness.
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 OGESTREL 0.5/50-21 vs ALYACEN 1/35, answered by our medical review team.
OGESTREL 0.5/50-21 is a Oral Contraceptive that works by Combination of norgestrel and ethinyl estradiol suppresses gonadotropin release, inhibiting ovulation; alters cervical mucus and endometrial lining.. 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 OGESTREL 0.5/50-21 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 OGESTREL 0.5/50-21 is: One tablet (norgestrel 0.5 mg / ethinyl estradiol 0.05 mg) orally once daily for 21 days, followed by 7 placebo days.. 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 OGESTREL 0.5/50-21 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. OGESTREL 0.5/50-21 is classified as Category C. Pregnancy category X. Contraindicated in pregnancy due to known teratogenicity. First trimester: limb defects, cardiac anomalies; second/third trimester: feminization of male fetus. 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.