Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DEMULEN 1/35-21 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 (estrogen) and ethynodiol diacetate (progestin). Inhibits gonadotropin secretion (FSH, LH) via negative feedback on hypothalamic-pituitary axis, suppressing ovulation. Additionally, thickens cervical mucus and alters 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,Treatment of moderate acne vulgaris in women at least 15 years old who have achieved menarche and are seeking contraception,Oral contraceptive for women over 35 who smoke (off-label: not recommended due to increased cardiovascular risk)
Prevention of pregnancy (FDA-approved)
One tablet orally once daily for 21 days, followed by 7 days off. Each tablet contains 1 mg ethynodiol diacetate and 35 mcg ethinyl estradiol.
One tablet (0.1 mg levonorgestrel, 0.02 mg ethinyl estradiol) orally once daily for 21 days, followed by 7 days of placebo.
Ethinyl estradiol: 13±3 hours (terminal); norethindrone: 8±3 hours. Steady-state achieved after ~5 days.
Terminal elimination half-life: 12–15 hours. Steady-state achieved within 5 days with Q12H dosing.
Ethinyl estradiol: primarily metabolized by CYP3A4 hydroxylation and conjugation; undergoes enterohepatic recirculation. Ethynodiol diacetate: rapidly deacetylated to norethindrone, which is metabolized by CYP3A4 and CYP2C9; undergoes reduction, hydroxylation, and 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 (primarily as glucuronide and sulfate conjugates): ~60%; fecal: ~40%
Renal: 50% as unchanged drug and metabolites; fecal: 40% as metabolites; biliary: ~10% as glucuronide conjugates.
Ethinyl estradiol: 97–98% bound to albumin; norethindrone: 93–97% bound to albumin and SHBG
~99% bound to serum albumin and sex hormone-binding globulin.
Ethinyl estradiol: 2.5–4 L/kg; norethindrone: 3.5–5 L/kg. Indicates extensive tissue distribution.
2.8 L/kg (apparent Vd), indicating extensive tissue distribution.
Ethinyl estradiol: ~45% (first-pass metabolism); norethindrone: ~65% (first-pass metabolism). Oral administration only.
Oral: ~70% due to first-pass metabolism.
No dose adjustment required for renal impairment. However, caution in severe renal impairment 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 and C (moderate to severe hepatic impairment). Use with caution in mild impairment (Child-Pugh A) with monitoring.
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 before menarche. Post-menarche: use same dosing as adults; monitor for bone health and growth.
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 due to lack of efficacy and increased thromboembolic risk.
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 combination oral contraceptive use. 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 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.
Increased risk of thromboembolic disorders (e.g., stroke, DVT, PE),Increased risk of myocardial infarction, especially in smokers and women with hypertension or hyperlipidemia,Hepatic neoplasia (benign/malignant),Gallbladder disease,Hypertension,Carbohydrate and lipid metabolism changes,Ocular lesions (e.g., retinal thrombosis),Depression,Fluid retention,Irregular bleeding,Possible reduced efficacy with enzyme-inducing drugs (e.g., rifampin, anticonvulsants),Chloasma,Pregnancy (should be ruled out before use)
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 (current or history),Cerebrovascular or coronary artery disease (current or history),Known or suspected breast carcinoma,Known or suspected estrogen-dependent neoplasia,Undiagnosed abnormal genital bleeding,Known or suspected pregnancy,Benign or malignant liver tumor (current or history),Severe hepatic impairment or acute liver disease,Hypersensitivity to any component,Age over 35 and smoking (≥15 cigarettes/day),Uncontrolled hypertension (systolic ≥160 mm Hg or diastolic ≥100 mm Hg),Diabetes with vascular involvement,Migraine with focal aura (if age ≥35),Major surgery with prolonged immobilization
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. Grapefruit juice may slightly increase estrogen levels but not clinically relevant. Avoid St. John's Wort as it reduces contraceptive efficacy. No dietary restrictions.
Grapefruit juice may increase ethinyl estradiol levels; avoid large quantities. No significant food restrictions. Administer with food if GI upset occurs.
First trimester: increased risk of cardiovascular defects (RR ~1.3) and oral clefts (RR ~1.1) with exposure; second and third trimesters: no proven association with major malformations, but may cause masculinization of female genitalia if high doses of progestins (ethynodiol diacetate is a weak progestin, risk low). Postnatal: potential for neonatal jaundice (due to estrogen).
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.
Excreted in breast milk in small amounts (estrogen and progestin levels ~1% of maternal dose; M/P ratio not well defined). May reduce milk quality and quantity; use only if benefits outweigh risks, preferably after weaning.
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.
No dose adjustments; contraindicated during pregnancy due to fetal risks. If used inadvertently, 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.
Demulen 1/35-21 (ethinyl estradiol 35 mcg, ethynodiol diacetate 1 mg) is a monophasic combined oral contraceptive. It has lower estrogen dose than many older pills but still carries thromboembolic risk. Advise patients to take at same time daily. Missed pill protocols: if missed >12 hours, take pill ASAP and continue; if missed 2 or more pills, use backup contraception for 7 days. Consider non-contraceptive benefits: improved cycle regularity, reduced dysmenorrhea, decreased acne. Monitor blood pressure and liver function. Contraindications: history of DVT/PE, active liver disease, breast cancer, pregnancy, migraine with aura. Smoking increases thromboembolic risk significantly, especially in women >35.
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 pill daily at the same time for 21 days, then no pills for 7 days; you will have withdrawal bleeding during the free week.,If you miss a pill by less than 12 hours, take it immediately and continue on schedule. If more than 12 hours, take the missed pill and use backup contraception (condoms) for the next 7 days.,Common side effects include nausea, headache, breast tenderness, breakthrough bleeding, and mood changes; these often improve after the first few months.,Seek medical help for symptoms of blood clots: sudden leg pain/swelling, chest pain, shortness of breath, sudden severe headache or vision changes.,Do not smoke while taking this medication; smoking increases risk of serious cardiovascular side effects, especially if over 35.,This pill does not protect against sexually transmitted infections; use condoms for STI prevention.
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 DEMULEN 1/35-21 vs AFIRMELLE, answered by our medical review team.
DEMULEN 1/35-21 is a Oral Contraceptive that works by Combination oral contraceptive containing ethinyl estradiol (estrogen) and ethynodiol diacetate (progestin). Inhibits gonadotropin secretion (FSH, LH) via negative feedback on hypothalamic-pituitary axis, suppressing ovulation. Additionally, thickens cervical mucus and alters 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 DEMULEN 1/35-21 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 DEMULEN 1/35-21 is: One tablet orally once daily for 21 days, followed by 7 days off. Each tablet contains 1 mg ethynodiol diacetate and 35 mcg ethinyl estradiol.. 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 DEMULEN 1/35-21 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. DEMULEN 1/35-21 is classified as Category C. First trimester: increased risk of cardiovascular defects (RR ~1.3) and oral clefts (RR ~1.1) with exposure; second and third trimesters: no proven association with major malformat. 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.