Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CYCLAFEM 1/35 vs AFIRMELLE
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 ethinyl estradiol and norethindrone. Suppresses gonadotropin (FSH, LH) secretion via estrogen and progestin negative feedback, inhibiting ovulation. Progestin alters cervical mucus (sperm penetration) and endometrial receptivity.
Combination oral contraceptive containing ethinyl estradiol and levonorgestrel. Inhibits ovulation by suppressing gonadotropin release (FSH and LH). Also increases cervical mucus viscosity and alters endometrial receptivity.
Prevention of pregnancy
Prevention of pregnancy (FDA-approved)
One tablet orally once daily. Each tablet contains 1 mg norethindrone and 0.035 mg ethinyl estradiol. Administer daily for 21 days followed by 7 days of placebo or no tablet.
One tablet (0.1 mg levonorgestrel, 0.02 mg ethinyl estradiol) orally once daily for 21 days, followed by 7 days of placebo.
Half-life of norethindrone is 5-14 hours; ethinyl estradiol is 10-20 hours. Steady state reached after 5-7 days.
Terminal elimination half-life: 12–15 hours. Steady-state achieved within 5 days with Q12H dosing.
Ethinyl estradiol: CYP3A4, sulfation, glucuronidation. Norethindrone: CYP3A4, reduction, conjugation.
Ethinyl estradiol undergoes first-pass metabolism in gut and liver via CYP3A4, with conjugation to sulfate and glucuronide. Levonorgestrel is metabolized primarily by CYP3A4 to reduced and hydroxylated metabolites, then conjugated.
Renal 40-60% as glucuronide and sulfate conjugates, biliary/fecal 20-40%.
Renal: 50% as unchanged drug and metabolites; fecal: 40% as metabolites; biliary: ~10% as glucuronide conjugates.
Norethindrone is 80-85% bound to SHBG and albumin; ethinyl estradiol is 95-98% bound to albumin.
~99% bound to serum albumin and sex hormone-binding globulin.
Norethindrone Vd is 1.2-2.4 L/kg; ethinyl estradiol Vd is 2.5-4.5 L/kg.
2.8 L/kg (apparent Vd), indicating extensive tissue distribution.
Oral bioavailability: norethindrone 50-60%; ethinyl estradiol 40-50% due to first-pass metabolism.
Oral: ~70% due to first-pass metabolism.
No dose adjustment required for mild to moderate renal impairment. Contraindicated in severe renal disease or acute renal failure due to potential fluid retention.
No dose adjustment required for mild to moderate renal impairment. Not recommended for use in end-stage renal disease.
Contraindicated in Child-Pugh class B or C (moderate to severe hepatic impairment). For Child-Pugh class A, use with caution and monitor liver function; no specific dose adjustment studied.
Contraindicated in acute hepatic disease or severe (Child-Pugh C) hepatic impairment. Use with caution in mild to moderate hepatic impairment; monitor liver function.
Not indicated for use in postmenarchal minors before menarche. For adolescents, same adult dosing (one tablet daily) after menarche. Safety and efficacy established in postmenarchal females.
Not indicated for use before menarche. Post-menarche: same as adult dosing (one tablet daily) based on adult clinical trials.
Not indicated for use in postmenopausal women. Avoid use in women over 50 years due to increased risk of thrombosis and no benefit for contraception. If used, no specific dose adjustment, but consider non-hormonal alternatives.
Not indicated for use in postmenopausal women; no specific dose adjustment required in healthy elderly, but limited data available.
Cigarette smoking increases risk of serious cardiovascular events from COC use. Risk increases with age and heavy smoking (>=15 cigarettes/day). Women over 35 who smoke should not use COCs.
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptive use. Risk increases with age (especially in women over 35) and with heavy smoking (15+ cigarettes/day). Women who use combination hormonal contraceptives should be strongly advised not to smoke.
Thrombotic disorders (DVT, PE, MI, stroke),Hepatic neoplasia (benign and malignant),Elevated blood pressure,Gallbladder disease,Carbohydrate/lipid metabolic effects,Hereditary angioedema exacerbation,Chloasma,Ocular lesions (retinal thrombosis, optic neuritis),Depression,Menstrual irregularities/breakthrough bleeding
Thrombotic disorders (venous thromboembolism, stroke, myocardial infarction),Cigarette smoking (increases cardiovascular risk),Hypertension (especially in women with renal disease or migraines),Gallbladder disease,Hepatic neoplasia (benign and malignant),Carbohydrate and lipid metabolism effects,Ocular lesions (retinal thrombosis),Depressed mood or depression,Uterine bleeding irregularities,Reduced efficacy with hepatic enzyme inducers
Thrombophlebitis or thromboembolic disorders,History of DVT/PE,Cerebrovascular or coronary artery disease,Known or suspected breast carcinoma,Estrogen-dependent neoplasia,Undiagnosed abnormal genital bleeding,Cholestatic jaundice of pregnancy/COC-related jaundice,Benign/malignant hepatic adenoma,Pregnancy,Hypersensitivity to any component,Age >35 and smoking >=15 cigarettes/day
Thrombophlebitis or thromboembolic disorders (current or history),Cerebrovascular or coronary artery disease (current or history),Known or suspected breast cancer, endometrial cancer, or other estrogen-dependent neoplasia,Undiagnosed abnormal genital bleeding,Cholestatic jaundice of pregnancy or jaundice with prior oral contraceptive use,Hepatic adenoma or carcinoma (current or history),Known or suspected pregnancy,Hypersensitivity to any component of the product,Heavy smoking (≥15 cigarettes/day) in women over 35
No significant food interactions. However, grapefruit juice may increase ethinyl estradiol levels via CYP3A4 inhibition, though clinical significance is uncertain. Avoid excessive alcohol intake as it may impair liver function and reduce contraceptive efficacy. Maintain a balanced diet, as folate supplementation may be beneficial due to potential folate depletion with oral contraceptives.
Grapefruit juice may increase ethinyl estradiol levels; avoid large quantities. No significant food restrictions. Administer with food if GI upset occurs.
Pregnancy category X. Contraindicated in pregnancy due to risk of fetal harm. First trimester: Increased risk of neural tube defects, cardiovascular anomalies, and limb reduction defects. Second and third trimesters: Associated with fetal genital abnormalities (masculinization of female fetuses) and potential for other congenital anomalies. Postnatal: Possible long-term neurodevelopmental effects.
Pregnancy category X. Contraindicated in pregnancy due to risk of fetal harm. First trimester: exposure associated with congenital anomalies (e.g., cardiovascular, neural tube defects). Second and third trimesters: increased risk of fetal growth restriction, preterm birth, and neonatal respiratory distress. Postnatal: possible long-term developmental effects.
Compatible with breastfeeding. Norethindrone and ethinyl estradiol are excreted in breast milk in small amounts. M/P ratio: Norethindrone ~0.5-0.7; ethinyl estradiol ~0.1-0.3. No adverse effects reported in infants at recommended doses. May reduce milk volume and protein content; use lowest effective dose.
Contraindicated during breastfeeding. Small amounts of ethinyl estradiol and norethindrone are excreted in breast milk; M/P ratio not well defined. Potential for adverse effects on infant (e.g., jaundice, breast enlargement). May reduce milk production and quality.
Not applicable; drug is contraindicated during pregnancy. No dose adjustments are recommended because use is contraindicated. If inadvertent exposure occurs, discontinue immediately.
Contraindicated in pregnancy; no dose adjustment recommended. If exposure occurs, immediate discontinuation is required. No pharmacokinetic data support safe use; avoid use entirely.
CYCLAFEM 1/35 is a monophasic oral contraceptive containing norethindrone (1 mg) and ethinyl estradiol (35 mcg). For missed pills: if one pill is missed, take it as soon as remembered, even if it means taking two pills in one day. If two pills are missed in Week 1 or 2, take two pills on the day remembered and two the next day, then resume regular schedule; use backup contraception for 7 days. If two pills are missed in Week 3 or three or more pills are missed at any time, discard the rest of the pack and start a new pack that day; use backup contraception for 7 days. Monitor for breakthrough bleeding, which is common in the first few cycles. Avoid use in women with uncontrolled hypertension, migraine with aura, or history of thromboembolism.
Afirmelle (levonorgestrel/ethinyl estradiol) is a combined oral contraceptive. Counsel patients to take at the same time daily to maintain consistent hormone levels. Use back-up contraception if a dose is missed. Monitor for signs of thromboembolism, especially in smokers over 35. Advise that certain antibiotics (e.g., rifampin) and anticonvulsants (e.g., phenytoin) may reduce efficacy. Consider progestin-only pill if contraindications to estrogen exist.
Take one tablet daily at the same time each day; do not skip doses.,If you miss a pill, refer to the missed pill instructions in the package insert or consult your healthcare provider.,Use additional non-hormonal contraception (e.g., condoms) for 7 days after missing pills as directed.,Report any signs of thromboembolism (leg pain, chest pain, shortness of breath) or stroke (sudden severe headache, visual changes, speech difficulty) immediately.,Smoking increases the risk of serious cardiovascular side effects; avoid smoking while taking this medication.,This medication does not protect against HIV or other sexually transmitted infections.,Expect spotting or light bleeding between periods, especially in the first few months.,If you have vomiting or diarrhea, use backup contraception and consult your healthcare provider.
Take one pill at the same time every day, even if you don't have sex.,If you miss a pill, follow the instructions in the package insert or ask your healthcare provider.,Use a backup method (like condoms) if you start late or miss pills.,This medication does not protect against HIV or other sexually transmitted infections.,Common side effects include nausea, breast tenderness, and breakthrough bleeding.,Seek medical help if you have symptoms of a blood clot: sudden chest pain, leg swelling, or shortness of breath.,Smoking while on this pill increases your risk of serious cardiovascular events.
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 1/35 vs AFIRMELLE, answered by our medical review team.
CYCLAFEM 1/35 is a Oral Contraceptive that works by Combination oral contraceptive containing ethinyl estradiol and norethindrone. Suppresses gonadotropin (FSH, LH) secretion via estrogen and progestin negative feedback, inhibiting ovulation. Progestin alters cervical mucus (sperm penetration) and endometrial receptivity.. AFIRMELLE is a Combined Oral Contraceptive that works by Combination oral contraceptive containing ethinyl estradiol and levonorgestrel. Inhibits ovulation by suppressing gonadotropin release (FSH and LH). Also increases cervical mucus viscosity and alters endometrial receptivity.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CYCLAFEM 1/35 and AFIRMELLE depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of CYCLAFEM 1/35 is: One tablet orally once daily. Each tablet contains 1 mg norethindrone and 0.035 mg ethinyl estradiol. Administer daily for 21 days followed by 7 days of placebo or no tablet.. The standard adult dose of AFIRMELLE is: One tablet (0.1 mg levonorgestrel, 0.02 mg ethinyl estradiol) orally once daily for 21 days, followed by 7 days of placebo.. 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 1/35 and AFIRMELLE 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 1/35 is classified as Category C. Pregnancy category X. Contraindicated in pregnancy due to risk of fetal harm. First trimester: Increased risk of neural tube defects, cardiovascular anomalies, and limb reduction d. AFIRMELLE is classified as Category C. Pregnancy category X. Contraindicated in pregnancy due to risk of fetal harm. First trimester: exposure associated with congenital anomalies (e.g., cardiovascular, neural tube defe. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.