Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
NORCEPT-E 1/35 28 vs ESTROSTEP FE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Combination estrogen (ethinyl estradiol) and progestin (norethindrone) contraceptive: suppresses gonadotropin release, inhibits ovulation, thickens cervical mucus, and alters endometrial lining.
Combination estrogen-progestin contraceptive: ethinyl estradiol suppresses gonadotropin release via negative feedback on hypothalamic-pituitary axis; norethindrone acetate produces progestational effects including endometrial transformation and cervical mucus thickening, inhibiting sperm penetration and implantation.
Prevention of pregnancy,Oral contraceptive
Prevention of pregnancy,Treatment of moderate acne vulgaris (in females ≥15 years with no known contraindications, who have achieved menarche)
1 tablet orally once daily for 21 days, followed by 7 days of placebo tablets.
One tablet daily orally, each tablet contains norethindrone acetate 1 mg and ethinyl estradiol 20 mcg (24 active tablets) followed by ferrous fumarate 75 mg tablets (4 placebo tablets).
Norethindrone: 5-14 hours; ethinyl estradiol: 13-27 hours. The terminal half-life of norethindrone is about 10 hours, allowing once-daily dosing; ethinyl estradiol's longer half-life contributes to steady-state concentrations within 3-5 days.
Ethinyl estradiol: 13-27 hours (terminal); norethindrone acetate: 5-14 hours. Clinical context: Steady-state reached within 7-10 days.
Ethinyl estradiol: primarily metabolized by CYP3A4; norethindrone: primarily metabolized by CYP3A4 and CYP2C9.
Ethinyl estradiol: primarily metabolized by CYP3A4; undergoes sulfation and glucuronidation. Norethindrone acetate: hydrolyzed to norethindrone, then metabolized by reduction and glucuronidation.
Renal (primarily as metabolites) and fecal; approximately 50-60% excreted in urine, 30-40% in feces. Ethinyl estradiol and norethindrone are extensively metabolized via hydroxylation and conjugation; glucuronide and sulfate conjugates are eliminated in urine and bile.
Renal: ~40% as metabolites; fecal: ~30% (biliary); remainder as conjugates.
Norethindrone: >97% bound to albumin and SHBG; ethinyl estradiol: >97% bound to albumin. Ethinyl estradiol also binds to SHBG with lower affinity.
Ethinyl estradiol: 97-98% bound to albumin and SHBG; norethindrone acetate: 91-95% bound to albumin and SHBG.
Norethindrone: approximately 3.5 L/kg; ethinyl estradiol: approximately 2.5 L/kg. These values reflect extensive tissue distribution and binding to tissues such as breast, uterus, and adipose.
Ethinyl estradiol: 2.3-3.6 L/kg; norethindrone acetate: 1.5-2.5 L/kg. Indicates extensive tissue distribution.
Oral: Norethindrone ~64% (first-pass metabolism); ethinyl estradiol ~40-50% (extensive first-pass metabolism). Factors such as food and individual differences may affect bioavailability.
Oral: Ethinyl estradiol ~45% (first-pass metabolism); norethindrone acetate ~64%.
No dose adjustment required for mild to moderate renal impairment. Contraindicated in acute renal disease or marked renal impairment.
No dose adjustment is recommended for patients with mild to moderate renal impairment. Use is contraindicated in patients with severely impaired renal function (GFR <30 m L/min/1.73 m²) due to potential for fluid retention and hyperkalemia.
Contraindicated in severe hepatic disease or liver tumors (benign or malignant). Use with caution in mild to moderate hepatic impairment; dose adjustment generally not required but monitor for adverse effects.
Contraindicated in patients with acute or chronic hepatic dysfunction (Child-Pugh class B or C). For mild hepatic impairment (Child-Pugh class A), use with caution and monitor liver function; no specific dose adjustment guidelines are established.
Not indicated for use before menarche. After menarche, use same adult dosing schedule.
Safety and efficacy have not been established in pediatric patients below 16 years of age. Post-pubertal adolescents may be dosed as adults, with careful consideration of risks (e.g., bone density).
No specific dose adjustment; use with caution due to increased risk of thromboembolic disorders and cardiovascular events in women over 35 who smoke.
Not indicated for use in women over 65 years due to lack of efficacy and safety data, and increased risk of cardiovascular and thrombotic events.
Cigarette smoking increases risk of serious cardiovascular events (thrombosis, stroke, myocardial infarction) from combination oral contraceptives, especially in women over 35 and heavy smokers (>15 cigarettes/day).
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptives. Risk increases with age and smoking intensity (especially >35 years). Women >35 years who smoke should not use this product.
Thrombotic disorders (DVT, PE, stroke, MI),Hepatic tumors,Hypertension,Gallbladder disease,Carbohydrate/lipid metabolism effects,Ocular lesions (retinal thrombosis),Hereditary angioedema,Chloasma,Depression
Thromboembolic disorders, cardiovascular disease (MI, stroke), hypertension, gallbladder disease, hepatic neoplasia, lipid effects, glucose intolerance, headache, breakthrough bleeding, depression, contact lens intolerance, fluid retention, hereditary angioedema.
Thrombophlebitis or thromboembolic disorders,History of DVT/PE,Cerebrovascular or coronary artery disease,Known or suspected breast cancer,Endometrial cancer 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
Thrombophlebitis or thromboembolic disorders, cerebrovascular or coronary artery disease, known or suspected breast carcinoma, endometrial carcinoma or other estrogen-dependent neoplasia, undiagnosed abnormal genital bleeding, cholestatic jaundice of pregnancy or jaundice with prior pill use, hepatic adenoma or carcinoma, pregnancy, hypersensitivity to any component.
No significant food interactions. Grapefruit juice does not affect ethinyl estradiol. Avoid St. John's wort (herbal supplement) as it reduces contraceptive efficacy.
No specific food interactions are reported for Estrostep Fe. Grapefruit juice may slightly increase estrogen levels but is not considered clinically significant. There are no dietary restrictions. However, patients should maintain a consistent intake of folic acid if planning pregnancy; iron supplements can be taken with food to reduce GI upset.
First trimester: Increased risk of neural tube defects, cardiovascular malformations, and limb reduction defects if inadvertently exposed to the progestin component (norethindrone) at high doses. Second and third trimesters: No evidence of teratogenicity from estrogen-progestin combinations; however, androgenic effects (pseudohermaphroditism in female fetuses) have been reported with high doses of progestins. Overall, combination oral contraceptives are contraindicated in pregnancy.
Category X. Estrostep FE (norethindrone acetate/ethinyl estradiol/ferrous fumarate) is contraindicated in pregnancy. First trimester: increased risk of neural tube defects, cardiovascular anomalies, and limb reduction defects from sex hormones. Second/third trimester: feminization of male fetus, potential for urogenital malformations, and long-term reproductive tract effects. Postnatal: possible increased risk of childhood cancers.
Small amounts of ethinyl estradiol and norethindrone are excreted into breast milk (M/P ratio for ethinyl estradiol approximately 0.75; for norethindrone, about 0.66). Use may reduce milk production and quality, especially in early postpartum. Avoid in nursing mothers unless essential; alternative contraception recommended.
Excreted in breast milk in small amounts (estrogen M/P ratio ~0.2, progestin M/P ratio ~0.6). May reduce milk quantity and quality. Use caution; generally not recommended. No adverse effects reported in infants at typical doses.
Contraindicated during pregnancy. No dose adjustments recommended as drug should be stopped immediately upon pregnancy diagnosis.
Contraindicated; no dose adjustment needed because drug should be discontinued immediately if pregnancy occurs. Pharmacokinetic changes in pregnancy (increased clearance, volume of distribution) not applicable due to contraindication.
NORCEPT-E 1/35 28 is a combination oral contraceptive containing ethinyl estradiol 35 mcg and norethindrone 1 mg. It is indicated for contraception and may be used off-label for menstrual disorders. Pearl: Counsel patients that missed pills increase pregnancy risk; refer to prescribing information for missed dose instructions. Monitor for thromboembolic events, especially in smokers over 35. Drug interactions: rifampin, certain anticonvulsants (e.g., phenytoin, carbamazepine), and St. John's wort reduce efficacy. Breakthrough bleeding common in first 3 cycles; if persistent, evaluate for non-compliance or alternative causes.
Estrostep Fe is a combined oral contraceptive containing norethindrone acetate and ethinyl estradiol. It is unique among OCPs for its step-up estrogen regimen (20, 30, 35 mcg EE) intended to mimic natural menstrual cycle. Clinicians should note that it is not FDA-approved for acne treatment, though it is often used off-label; only Estrostep (non-Fe) is approved for acne. The iron (ferrous fumarate) in the last 7 tablets is a placebo. It is a low-dose pill; missed doses more likely cause breakthrough bleeding. Contraindications include smoking >35, history of DVT/PE, migraine with aura, liver disease, breast cancer. Counsel patients to take at same time daily; if missed, follow standard missed pill protocol.
Take one pill daily at the same time, preferably after an evening meal or at bedtime to minimize nausea.,Missed pill? Take as soon as remembered; if >48 hours, use backup contraception (condoms) for 7 days and consult the package insert.,Report immediately: severe leg pain/chest pain/sudden shortness of breath (signs of blood clot), severe headache, vision changes, or jaundice.,Smoking increases risk of serious cardiovascular side effects; avoid smoking especially if over 35.,May decrease efficacy with certain antibiotics (non-rifampin) – use backup contraception during antibiotic course and for 7 days after.,Do not take if pregnant, breastfeeding, or have history of blood clots, stroke, breast cancer, liver disease, or migraine with aura.
Take one pill at the same time each day. The first 21 pills contain active hormones; the last 7 pills are iron tablets (not hormones).,If you miss a pill, refer to the package insert or contact your healthcare provider. Use backup contraception (condoms) if pills are missed.,Common side effects include nausea, breast tenderness, headache, and breakthrough bleeding, especially in the first few months.,Estrostep Fe does not protect against sexually transmitted infections (STIs). Always use condoms for STI prevention.,Smoking while using this pill increases risk of serious cardiovascular events. Do not smoke.,Contact your doctor if you experience signs of a blood clot: sudden leg pain/swelling, chest pain, shortness of breath, or sudden severe headache.,The iron in the last 7 pills is to help with iron levels but does not provide hormonal contraception during that week.
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 NORCEPT-E 1/35 28 vs ESTROSTEP FE, answered by our medical review team.
NORCEPT-E 1/35 28 is a Combined Oral Contraceptive that works by Combination estrogen (ethinyl estradiol) and progestin (norethindrone) contraceptive: suppresses gonadotropin release, inhibits ovulation, thickens cervical mucus, and alters endometrial lining.. ESTROSTEP FE is a Combined Oral Contraceptive that works by Combination estrogen-progestin contraceptive: ethinyl estradiol suppresses gonadotropin release via negative feedback on hypothalamic-pituitary axis; norethindrone acetate produces progestational effects including endometrial transformation and cervical mucus thickening, inhibiting sperm penetration and implantation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between NORCEPT-E 1/35 28 and ESTROSTEP FE depend on the specific clinical indication. These are both Combined 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 NORCEPT-E 1/35 28 is: 1 tablet orally once daily for 21 days, followed by 7 days of placebo tablets.. The standard adult dose of ESTROSTEP FE is: One tablet daily orally, each tablet contains norethindrone acetate 1 mg and ethinyl estradiol 20 mcg (24 active tablets) followed by ferrous fumarate 75 mg tablets (4 placebo 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 NORCEPT-E 1/35 28 and ESTROSTEP FE 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. NORCEPT-E 1/35 28 is classified as Category C. First trimester: Increased risk of neural tube defects, cardiovascular malformations, and limb reduction defects if inadvertently exposed to the progestin component (norethindrone). ESTROSTEP FE is classified as Category C. Category X. Estrostep FE (norethindrone acetate/ethinyl estradiol/ferrous fumarate) is contraindicated in pregnancy. First trimester: increased risk of neural tube defects, cardiov. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.