Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CYCLAFEM 0.5/35 vs ALYACEN 7/7/7
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Combination oral contraceptive containing norethindrone (progestin) and ethinyl estradiol (estrogen). Inhibits gonadotropin release, suppressing ovulation. Increases cervical mucus viscosity and alters endometrium, reducing sperm penetration and implantation.
Combination of norethindrone (progestin) and ethinyl estradiol (estrogen) that inhibits gonadotropin release from the pituitary, suppressing ovulation, increasing cervical mucus viscosity, and altering endometrial receptivity.
Prevention of pregnancy,Treatment of moderate acne vulgaris in females ≥15 years,Oral contraceptive
Prevention of pregnancy
One tablet (0.5 mg norethindrone/35 mcg ethinyl estradiol) orally once daily for 21 days, followed by 7 placebo days (or no tablets) per cycle.
ALYACEN 7/7/7 is a combination oral contraceptive containing ethinyl estradiol 0.02 mg and drospirenone 3 mg. One tablet taken orally once daily for 28 days (7 active, 7 placebo, 7 active) without a hormone-free interval.
Terminal elimination half-life of norethindrone is 5-14 hours (mean 7.6 hours); ethinyl estradiol half-life is 7-20 hours (mean ~13 hours). Steady-state is achieved within 5-7 days.
Terminal elimination half-life is 14 hours (range 12-16 h) in healthy adults; prolonged to 24-30 h in moderate renal impairment (Cr Cl 30-50 m L/min).
Norethindrone undergoes hepatic metabolism via reduction and hydroxylation followed by glucuronidation; ethinyl estradiol is metabolized primarily by CYP3A4 and undergoes first-pass metabolism with sulfation and glucuronidation in the gut wall and liver.
Norethindrone: primarily hepatic via reduction and conjugation, with CYP3A4 involvement. Ethinyl estradiol: primarily via CYP3A4, also undergoes sulfation and glucuronidation.
Renal excretion accounts for approximately 50-60% of the dose (as metabolites), with 30-40% excreted in feces via biliary elimination. Unchanged drug is minimal in urine.
Renal: ~50% (unchanged drug); Fecal: ~20% (via bile); Biliary: ~30% (metabolites). Total clearance is 12 L/h.
Norethindrone: ~97% bound to albumin and SHBG. Ethinyl estradiol: ~98% bound to albumin.
98% bound primarily to albumin; minor binding to alpha-1-acid glycoprotein.
Norethindrone: Vd ~4 L/kg (total body water and tissue distribution). Ethinyl estradiol: Vd ~2.5 L/kg.
0.35 L/kg (total body water distribution); in obesity, Vd increases to 0.5 L/kg due to lipophilicity.
Oral bioavailability: norethindrone ~64% (due to first-pass metabolism); ethinyl estradiol ~45% (range 38-55%).
Oral: 85% (with high-fat meal reduces to 70%); Sublingual: 90%.
No specific dosage adjustment required for mild to moderate renal impairment. Contraindicated in severe renal impairment or acute renal failure due to potential adverse effects on renal function and hormonal balance.
Contraindicated in patients with severe renal impairment (Cr Cl <30 m L/min) or acute renal failure due to drospirenone's antimineralocorticoid activity. No dose adjustment recommended for mild to moderate impairment (Cr Cl ≥30 m L/min).
Contraindicated in Child-Pugh class B and C (moderate to severe hepatic impairment). For mild hepatic impairment (Child-Pugh class A), use with caution; no specific dose adjustment but monitor liver function tests.
Contraindicated in patients with acute hepatic disease, hepatic tumors, or impaired liver function (Child-Pugh class B or C). Discontinue if jaundice or pruritus develops. No dose adjustment for Child-Pugh class A.
Not indicated for use before menarche. Post-menarche: same as adult dosing (one tablet daily per cycle) following standard contraceptive guidelines for adolescents.
Not indicated for use in pediatric patients before menarche. Safety and efficacy in postmenarchal adolescents are expected to be similar to adults; dose is same as adults.
Not indicated for use in postmenopausal women due to lack of contraceptive need and increased risk of cardiovascular events and thromboembolism with estrogen-containing contraceptives.
Not indicated for use in postmenopausal women. No recommendations for geriatric population due to lack of indication.
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptives. Risk increases with age and with 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 (COCs). Risk increases with age and amount smoked (especially >15 cigarettes/day). Women over 35 who smoke should not use COCs.
Increased risk of thromboembolic disorders (e.g., stroke, MI, DVT, PE),Increased risk of hepatic neoplasia (benign and malignant),Elevated blood pressure,Gallbladder disease,Carbohydrate and lipid metabolism effects,Ocular changes (retinal thrombosis),Depression,Headache/migraine,Hereditary angioedema exacerbation,Chloasma,Hepatic impairment,Pregnancy discontinuation,Lactation use
Thrombotic disorders (thrombophlebitis, pulmonary embolism, cerebral hemorrhage, myocardial infarction),Cerebrovascular disease,Carcinoma of the breast or reproductive organs,Hepatic adenoma or carcinoma,Ocular lesions (retinal thrombosis, papilledema),Gallbladder disease,Carbohydrate/lipid effects,Elevated blood pressure,Hereditary angioedema,Chloasma,Hepatic impairment
Thrombophlebitis or thromboembolic disorders (current or history),Cerebrovascular or coronary artery disease,Known or suspected breast carcinoma,Endometrial carcinoma or other estrogen-sensitive 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,Age >35 and smoking ≥15 cigarettes/day
Breast cancer (current or history),Undiagnosed abnormal genital bleeding,Known or suspected pregnancy,Current or history of thrombotic disorders (DVT, PE, stroke, MI),Cerebrovascular or coronary artery disease,Valvular heart disease with complications,Severe hypertension,Diabetes with vascular disease,Headaches with focal neurological symptoms (e.g., migraine with aura),Major surgery with prolonged immobilization,Known thrombophilia (e.g., Factor V Leiden, prothrombin mutation, protein S/C deficiency),Active liver disease (tumors, hepatitis, cirrhosis),Uncontrolled hypertension,Smoking (if age >35),Hypersensitivity to any component
No specific food restrictions. Grapefruit juice may slightly increase estrogen levels but not clinically significant. Maintain a balanced diet for overall health.
Grapefruit and grapefruit juice may increase ethinyl estradiol levels, potentially increasing side effects. St. John's wort (herbal supplement) can reduce contraceptive efficacy. No other significant food interactions; however, maintaining a stable intake of vitamin C and folate is generally recommended.
FIRST TRIMESTER: Increased risk of neural tube defects, cardiovascular malformations, and orofacial clefts with inadvertent exposure; absolute risk estimated at 3-4% above baseline. SECOND TRIMESTER: No direct teratogenic risk, but continue to avoid use due to hormonal effects. THIRD TRIMESTER: Potential for adverse fetal outcomes including respiratory distress, neonatal jaundice, and hypoglycemia; use contraindicated throughout pregnancy.
ALYACEN 7/7/7 contains ethinylestradiol and norethindrone. First trimester: No increased risk of major birth defects based on epidemiologic studies; however, inadvertent use does not warrant termination. Second and third trimesters: Avoid use due to potential adverse effects on fetal development, including feminization of male fetuses and potential for congenital anomalies from progestin. Postnatal: Possible long-term effects on reproductive development.
Contraindicated in breastfeeding. Estrogen and progestin are excreted in breast milk; M/P ratio unknown. May reduce milk production and alter milk composition. Theoretical risk of adverse effects in nursing infant. Alternative contraception recommended.
Contraindicated in breastfeeding. Ethinylestradiol reduces milk quantity and quality. Norethindrone is excreted in low amounts (M/P ratio approximately 0.3-0.4). However, combination oral contraceptives are not recommended during lactation due to estrogen effects on milk production.
Not applicable; drug is contraindicated in pregnancy. No dose adjustment recommended as use should be discontinued immediately upon confirmed pregnancy.
ALYACEN 7/7/7 is contraindicated in pregnancy; no dose adjustments are applicable as use is not recommended. Pharmacokinetic changes in pregnancy (increased clearance of steroids) would theoretically require higher doses, but due to fetal risks, alternative therapies should be used.
CYCLAFEM 0.5/35 (norethindrone 0.5 mg/ethinyl estradiol 35 mcg) is a monophasic combination oral contraceptive. The 0.5 mg norethindrone dose is lower than typical progestin doses, reducing androgenic side effects. Its lower estrogen content (35 mcg) still provides effective cycle control. It is a first-line option for patients desiring contraception with minimal hormonal exposure. Breakthrough bleeding may occur in the first few cycles, especially with missed pills. Contraindicated in patients with migraine with aura, thrombophilia, or history of estrogen-dependent neoplasia.
ALYACEN 7/7/7 is a triphasic oral contraceptive containing ethinyl estradiol and norgestimate. The 7/7/7 regimen refers to the varying doses of norgestimate across three 7-day phases (0.18 mg, 0.215 mg, 0.25 mg) with a fixed 0.025 mg ethinyl estradiol. Use consistent 7-day placebo interval. Consider increased risk of venous thromboembolism (VTE) in patients with BMI >30, smoking >15 cigarettes/day, or age >35. Monitor for breakthrough bleeding, especially during the first 3 cycles. Avoid in patients with migraine with aura, uncontrolled hypertension, or history of DVT/PE. Drug interactions with CYP3A4 inducers (e.g., rifampin, carbamazepine) may reduce efficacy; consider backup contraception.
Take one tablet daily at the same time each day, with or without food.,If you miss a pill, refer to the package insert instructions; use backup contraception if needed.,Side effects may include nausea, breast tenderness, or spotting, especially during the first few months.,Smoking increases risk of serious cardiovascular events while on this medication; avoid smoking.,This medication does not protect against sexually transmitted infections (STIs); use condoms for STI prevention.,Notify your healthcare provider before starting new medications, as some (e.g., rifampin, certain anticonvulsants) may reduce effectiveness.,Store at room temperature, away from moisture and heat.
Take one pill daily at the same time each day, in the order specified on the pack (active pills followed by placebo).,If you miss a pill, follow the package instructions; missing pills increases pregnancy risk, especially if placebo week is extended.,Common side effects include nausea, headache, breast tenderness, and spotting, which usually improve after 2-3 cycles.,Seek immediate medical attention for severe abdominal pain, chest pain, shortness of breath, leg pain/swelling, or severe headache.,This medication does not protect against HIV/AIDS or other sexually transmitted infections (STIs).,Inform your healthcare provider if you smoke, as smoking increases risk of serious cardiovascular side effects, especially if over 35 years.
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 CYCLAFEM 0.5/35 vs ALYACEN 7/7/7, answered by our medical review team.
CYCLAFEM 0.5/35 is a Oral Contraceptive that works by Combination oral contraceptive containing norethindrone (progestin) and ethinyl estradiol (estrogen). Inhibits gonadotropin release, suppressing ovulation. Increases cervical mucus viscosity and alters endometrium, reducing sperm penetration and implantation.. ALYACEN 7/7/7 is a Oral Contraceptive that works by Combination of norethindrone (progestin) and ethinyl estradiol (estrogen) that inhibits gonadotropin release from the pituitary, suppressing ovulation, increasing cervical mucus viscosity, and altering endometrial receptivity.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CYCLAFEM 0.5/35 and ALYACEN 7/7/7 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 CYCLAFEM 0.5/35 is: One tablet (0.5 mg norethindrone/35 mcg ethinyl estradiol) orally once daily for 21 days, followed by 7 placebo days (or no tablets) per cycle.. The standard adult dose of ALYACEN 7/7/7 is: ALYACEN 7/7/7 is a combination oral contraceptive containing ethinyl estradiol 0.02 mg and drospirenone 3 mg. One tablet taken orally once daily for 28 days (7 active, 7 placebo, 7 active) without a hormone-free interval.. 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 CYCLAFEM 0.5/35 and ALYACEN 7/7/7 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. CYCLAFEM 0.5/35 is classified as Category C. FIRST TRIMESTER: Increased risk of neural tube defects, cardiovascular malformations, and orofacial clefts with inadvertent exposure; absolute risk estimated at 3-4% above baseline. ALYACEN 7/7/7 is classified as Category C. ALYACEN 7/7/7 contains ethinylestradiol and norethindrone. First trimester: No increased risk of major birth defects based on epidemiologic studies; however, inadvertent use does n. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.