Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
MICROGESTIN FE 1.5/30 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 oral contraceptive: ethinyl estradiol (estrogen) and norethindrone acetate (progestin) suppress gonadotropin (FSH, LH) release, preventing ovulation; increase cervical mucus viscosity, inhibiting sperm penetration; alter endometrial development, reducing 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,Treatment of moderate acne vulgaris in women >=15 years who have achieved menarche and are not pregnant or otherwise contraindicated,Treatment of heavy menstrual bleeding (off-label),Emergency contraception (off-label)
Prevention of pregnancy
One tablet (norethindrone acetate 1.5 mg, ethinyl estradiol 30 mcg) orally once daily for 28-day cycles (21 active tablets + 7 ferrous fumarate tablets).
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.
Norethindrone: 6-8 hours (terminal); Ethinyl estradiol: 12-18 hours (terminal). Clinical context: Steady-state achieved within 5-7 days; dosing interval suitable for once-daily administration.
Norethindrone: 8-11 hours (terminal); ethinyl estradiol: 10-20 hours (terminal). The half-life supports once-daily dosing for oral contraceptive efficacy.
Ethinyl estradiol: primarily metabolized via CYP3A4; undergoes first-pass metabolism in gut and liver. Norethindrone acetate: deacetylated to norethindrone, metabolized mainly via reduction and conjugation (glucuronidation, sulfation), partly by CYP3A4.
Ethinyl estradiol: primarily hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Norethindrone: 50-60% renal (as metabolites), 20-40% fecal; Ethinyl estradiol: ~40% renal, ~60% fecal (as glucuronide/sulfate conjugates).
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%).
Norethindrone: ~97% albumin and SHBG; Ethinyl estradiol: ~98% albumin (induces SHBG synthesis).
Norethindrone: 61% bound to albumin and SHBG; ethinyl estradiol: 97-98% bound to albumin.
Norethindrone: 2-5 L/kg (wide distribution, including breast tissue and adipose); Ethinyl estradiol: 2-4 L/kg (extensive distribution into reproductive tissues).
Norethindrone: 3.8-4.5 L/kg; ethinyl estradiol: 2.0-4.0 L/kg. Large Vd indicates extensive tissue distribution.
Norethindrone: ~64% (oral, first-pass metabolism); Ethinyl estradiol: ~40-45% (oral, 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 (e GFR ≥30 m L/min/1.73 m²). Not recommended in severe impairment (e GFR <30 m L/min/1.73 m²) due to limited data.
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 Child-Pugh class B or C (moderate to severe hepatic impairment). For Child-Pugh class A (mild impairment), use with caution; no specific dose adjustment established, but may increase risk of adverse effects.
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 for postmenarcheal adolescents. Dose same as adults: one tablet orally once daily for 28-day cycles. Not indicated for premenarcheal patients.
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 women over 65 years due to lack of efficacy and safety data; increased risk of thromboembolic events and cardiovascular disease outweighs potential benefit.
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 >=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.
Thrombotic disorders (venous thromboembolism, arterial thrombosis, stroke, MI),Carcinoma of breast/cervix,Hepatic disease (jaundice, tumors),Elevated blood pressure,Gallbladder disease,Carbohydrate/lipid effects,Headache/migraine,Vaginal bleeding irregularities,Depression,Hereditary angioedema,Chloasma,Pregnancy loss
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 DVT/PE,Cerebrovascular or coronary artery disease,Known or suspected breast carcinoma,Carcinoma of endometrium or other estrogen-dependent neoplasia,Undiagnosed abnormal genital bleeding,Cholestatic jaundice of pregnancy or jaundice with prior pill use,Hepatic adenoma/carcinoma,Known or suspected pregnancy,Hypersensitivity to any component,Smoking in women >=35 years,Uncontrolled hypertension,Diabetes with vascular involvement,Major surgery with prolonged immobilization
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 increase estrogen levels but no specific restriction is required. Iron tablets should be taken on an empty stomach for best absorption, but can be taken with food if GI upset occurs.
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. First trimester: No increased risk of major birth defects from inadvertent use, but post-fertilization effects are theoretical. Contraindicated in pregnancy due to estrogen component and progestin exposure. Second/third trimester: Irrelevant as drug is contraindicated; no fetal exposure studies. Use in pregnancy may cause fetal harm: possible congenital anomalies (limb defects, heart defects) and adverse outcomes (low birth weight, premature birth, neonatal withdrawal) with prolonged exposure.
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).
Small amounts of ethinyl estradiol and norethindrone acetate are excreted in breast milk (estimated ~0.1% of maternal dose). M/P ratio not established. No adverse effects on nursing infant or milk production reported with combined oral contraceptives; however, WHO recommends avoiding combined OCs during lactation until weaning or at least 6 months postpartum due to theoretical risk of estrogen affecting milk production. Use caution; consider progestin-only alternative.
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; no dose adjustment applicable. If pregnancy occurs, discontinue drug immediately. No pharmacokinetic data indicating need for dose changes in pregnancy because drug is not used during pregnancy.
Contraindicated in pregnancy; no dose adjustments applicable. Discontinue medication immediately upon pregnancy detection.
MICROGESTIN FE 1.5/30 contains norethindrone acetate 1.5 mg and ethinyl estradiol 30 mcg, plus ferrous fumarate (iron) tablets. The iron tablets are not part of the contraceptive regimen and should be taken only if iron deficiency is a concern. Because it is a combination oral contraceptive (COC), it has higher estrogen content compared to low-dose pills, which may increase the risk of thromboembolism. It is indicated for contraception and may also be used for menstrual disorders. The ring in the package is a placebo indicator; be aware that patients may confuse the iron tablets for active pills.
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 active pill at the same time each day, followed by the brown iron tablets during the last 7 days of the pack.,If you miss a dose, follow the package instructions: take the missed pill as soon as remembered, and use backup contraception if more than one pill is missed.,Smoking increases the risk of serious cardiovascular side effects from birth control pills, especially if you are over 35.,Common side effects include nausea, breast tenderness, and breakthrough bleeding, which often resolve within a few months.,This pill 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 MICROGESTIN FE 1.5/30 vs ALYACEN 1/35, answered by our medical review team.
MICROGESTIN FE 1.5/30 is a Oral Contraceptive that works by Combination oral contraceptive: ethinyl estradiol (estrogen) and norethindrone acetate (progestin) suppress gonadotropin (FSH, LH) release, preventing ovulation; increase cervical mucus viscosity, inhibiting sperm penetration; alter endometrial development, reducing 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 MICROGESTIN FE 1.5/30 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 MICROGESTIN FE 1.5/30 is: One tablet (norethindrone acetate 1.5 mg, ethinyl estradiol 30 mcg) orally once daily for 28-day cycles (21 active tablets + 7 ferrous fumarate tablets).. 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 MICROGESTIN FE 1.5/30 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. MICROGESTIN FE 1.5/30 is classified as Category C. FDA Pregnancy Category X. First trimester: No increased risk of major birth defects from inadvertent use, but post-fertilization effects are theoretical. Contraindicated in pregnan. 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.