Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
MODEYSO vs DEMULEN 1/50-21
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
The mechanism of action of MODEYSO (elacestrant) is not fully elucidated. Elacestrant is an estrogen receptor antagonist that binds to estrogen receptor alpha (ERα) and degrades it, inhibiting estrogen-mediated signaling and tumor growth in ER-positive breast cancer.
DEMULEN 1/50-21 is a combined oral contraceptive containing ethinyl estradiol and ethynodiol diacetate. Ethinyl estradiol and progestins inhibit gonadotropin release (FSH and LH) from the pituitary, suppressing ovulation. Progestins also increase cervical mucus viscosity and alter endometrial receptivity, impeding sperm penetration and implantation.
Treatment of postmenopausal women or adult men with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative, ESR1-mutated advanced or metastatic breast cancer with disease progression following at least one line of endocrine therapy.
Prevention of pregnancy,Treatment of moderate acne vulgaris (off-label use)
400 mg orally once daily with food
1 tablet (ethinyl estradiol 50 mcg, norethindrone 1 mg) orally once daily for 21 days, followed by 7 days off.
Terminal half-life approximately 6 days (range 4–10 days) in healthy subjects; supports weekly dosing interval
Ethinylestradiol: 13 ± 3 h (biphasic; terminal phase used for dosing interval). Clinical context: steady-state achieved after ~3 days; missed dose may reduce contraceptive efficacy if >36 h.
Elacestrant is metabolized primarily by CYP3A4 and CYP2C8.
Ethinyl estradiol undergoes first-pass metabolism in the gut wall and liver, with hydroxylation by CYP3A4 and conjugation via glucuronidation and sulfation. Ethynodiol diacetate is rapidly deacetylated to norethindrone, which is metabolized by reduction and conjugation, with CYP3A4 as a minor pathway.
Renal excretion unchanged: <1%; biliary/fecal elimination: >99% as unchanged drug
Renal (approx. 50% as metabolites, <1% unchanged), fecal (approx. 40%, largely as ethinylestradiol conjugates), biliary (minor, enterohepatic recirculation of ethinylestradiol)
Negligible (<2%) binding to plasma proteins
Ethinylestradiol: 97-98% bound to serum albumin (primarily) and SHBG; ethynodiol diacetate: >95% bound to albumin and SHBG.
Vd approximately 0.15 L/kg, consistent with distribution primarily in blood volume
Ethinylestradiol: 2.8-4.3 L/kg (extensive tissue distribution, including breast and reproductive tissues); ethynodiol: 1.5-2.0 L/kg.
Intravenous only; bioavailability 100%
Oral: Ethinylestradiol 38-48% (first-pass metabolism); ethynodiol diacetate ~60% (rapid hydrolysis to active norethindrone).
No dosage adjustment required for mild to moderate renal impairment (GFR ≥30 m L/min). Not recommended in severe renal impairment (GFR <30 m L/min) or end-stage renal disease.
No dose adjustment required for mild-moderate renal impairment. Avoid use in severe renal impairment or dialysis due to potential fluid retention and electrolyte disturbances.
Mild hepatic impairment (Child-Pugh A): No adjustment. Moderate hepatic impairment (Child-Pugh B): Reduce to 200 mg once daily. Severe hepatic impairment (Child-Pugh C): Avoid use.
Contraindicated in acute or chronic hepatic dysfunction, including Child-Pugh class A, B, or C. Use in mild hepatic impairment not recommended.
Safety and efficacy not established in pediatric patients. No recommended dosage.
Not indicated for use before menarche. For post-menarcheal adolescents, same dosing as adults. Safety and efficacy established in post-pubertal females.
No specific dosage adjustment recommended; monitor renal function due to age-related decline.
Not indicated after menopause. Risk of thromboembolic events outweighs benefits in women over 35 who smoke or have cardiovascular risk factors.
No black box warning.
Cigarette smoking increases the risk of serious cardiovascular events from oral contraceptive use. This risk increases with age and with the number of cigarettes smoked, and is quite marked in women over 35 years of age. Women who use oral contraceptives should be strongly advised not to smoke.
Dysphagia and esophageal injury risk: Instruct patients to take MODEYSO with water, swallow whole, and not to crush or chew. Advise patients to report signs of esophageal injury.,Embryo-fetal toxicity: Can cause fetal harm. Advise females of reproductive potential to use effective contraception during treatment and for 1 week after the last dose.
Increased risk of thrombotic disorders (venous thromboembolism, stroke, myocardial infarction),Cigarette smoking increases cardiovascular risk, especially in women over 35,Increased risk of hypertension, gallbladder disease, and hepatic neoplasia,Risk of retinal thrombosis; discontinue if unexplained vision loss occurs,May cause fluid retention; use with caution in conditions affected by fluid retention,May induce cholestatic jaundice; discontinue if jaundice develops,May cause carbohydrate and lipid metabolism changes
None known.
Known or suspected pregnancy,Current or past history of 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 oral contraceptive use,Hepatic adenoma or carcinoma,Active liver disease (e.g., acute viral hepatitis, decompensated cirrhosis),Hypersensitivity to any component
No specific food interactions. Grapefruit juice may increase estrogen levels due to CYP3A4 inhibition, but clinical significance is unknown. Avoid St. John's Wort as it reduces contraceptive efficacy by inducing CYP3A4.
No specific food interactions. Oral contraceptives may increase caffeine levels; limit caffeine intake if side effects like jitteriness occur. Grapefruit and grapefruit juice do not significantly affect this medication.
MODEYSO (mifepristone) is contraindicated in pregnancy for elective abortion. If inadvertently used during early pregnancy, there is a risk of complete abortion. In later pregnancy, it is used as part of medical abortion regimen. No known teratogenic effects if pregnancy continues after failed abortion, but data are limited.
First trimester: Use contraindicated due to increased risk of congenital anomalies, particularly cardiovascular defects and limb reduction defects, associated with sex hormones. Second and third trimesters: Avoid due to risk of fetal harm, including masculinization of female fetus with progestins; also associated with increased risk of neonatal jaundice and liver dysfunction.
Mifepristone is excreted into breast milk in low amounts; relative infant dose estimated <1%. M/P ratio approximately 0.5. Consider temporary discontinuation of breastfeeding for 1-2 days after administration.
Small amounts of ethinyl estradiol and ethynodiol diacetate are excreted in breast milk. M/P ratio not established. Estrogen-progestin combinations may reduce milk production and alter milk composition; use during breastfeeding is generally not recommended. Consider alternative contraception.
No dose adjustment needed for mifepristone in pregnancy as it is used at standard doses for medical abortion. Pharmacokinetic changes in pregnancy (increased volume of distribution) do not necessitate dose alteration due to its single-dose regimen.
Not applicable as use is contraindicated during pregnancy. No pharmacokinetic studies have been conducted to recommend dose adjustments.
MODEYSO (drospirenone/estetrol) is a combined oral contraceptive containing estetrol, a fetal estrogen with unique tissue selectivity. It has a shorter half-life than ethinyl estradiol, potentially reducing thrombotic risk. Monitor potassium levels in patients with renal impairment or those on potassium-sparing diuretics due to drospirenone's antimineralocorticoid activity. Breakthrough bleeding may be more common in the first few cycles. Contraindicated in patients with liver disease, history of DVT/PE, or migraines with aura.
DEMULEN 1/50-21 is a monophasic oral contraceptive containing ethinyl estradiol 50 mcg and ethynodiol diacetate 1 mg. Use with caution in patients over 35 who smoke due to increased cardiovascular risk. Monitor for breakthrough bleeding, especially in the first three cycles. Consider drug interactions with rifampin, anticonvulsants, and broad-spectrum antibiotics. Administer at the same time daily to maintain efficacy. The 21-day regimen requires a 7-day pill-free interval. Instruct to start on first day of menses or first Sunday after onset.
Take one tablet daily at the same time, with or without food. Do not skip doses.,If you miss a dose, follow the patient leaflet instructions; use backup contraception if needed.,Smoking increases risk of serious cardiovascular side effects; avoid smoking especially if over 35 years old.,Report symptoms of blood clots: sudden leg pain/swelling, chest pain, shortness of breath, or sudden vision changes.,May cause irregular bleeding initially; consult your healthcare provider if bleeding is prolonged or heavy.,Do not take with other medications that increase potassium (e.g., NSAIDs, ACE inhibitors, potassium supplements) without medical advice.
Take one tablet daily at the same time, starting on the first day of your menstrual period or the first Sunday after your period begins.,Swallow tablet whole with water, with or without food.,After finishing all 21 tablets, wait 7 days before starting a new pack. You will have a withdrawal bleed during this time.,If you miss a tablet by less than 12 hours, take it immediately. If more than 12 hours, take the missed tablet and use backup contraception for 7 days.,Seek emergency medical care for symptoms of blood clots (sudden severe headache, chest pain, shortness of breath, leg pain/swelling), stroke (sudden numbness/weakness, slurred speech), or liver problems (yellowing skin/eyes, dark urine).,Avoid smoking while taking this medication, especially if over age 35, due to increased risk of cardiovascular events.,Inform your healthcare provider about all other medications (including over-the-counter drugs, herbal supplements like St. John's Wort) as they may reduce contraceptive efficacy.,This medication does not protect against HIV or other sexually transmitted infections.
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 MODEYSO vs DEMULEN 1/50-21, answered by our medical review team.
MODEYSO is a Combination Oral Contraceptive that works by The mechanism of action of MODEYSO (elacestrant) is not fully elucidated. Elacestrant is an estrogen receptor antagonist that binds to estrogen receptor alpha (ERα) and degrades it, inhibiting estrogen-mediated signaling and tumor growth in ER-positive breast cancer.. DEMULEN 1/50-21 is a Combination Oral Contraceptive that works by DEMULEN 1/50-21 is a combined oral contraceptive containing ethinyl estradiol and ethynodiol diacetate. Ethinyl estradiol and progestins inhibit gonadotropin release (FSH and LH) from the pituitary, suppressing ovulation. Progestins also increase cervical mucus viscosity and alter endometrial receptivity, impeding sperm penetration and implantation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between MODEYSO and DEMULEN 1/50-21 depend on the specific clinical indication. These are both Combination 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 MODEYSO is: 400 mg orally once daily with food. The standard adult dose of DEMULEN 1/50-21 is: 1 tablet (ethinyl estradiol 50 mcg, norethindrone 1 mg) orally once daily for 21 days, followed by 7 days off.. 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 MODEYSO and DEMULEN 1/50-21 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. MODEYSO is classified as Category C. MODEYSO (mifepristone) is contraindicated in pregnancy for elective abortion. If inadvertently used during early pregnancy, there is a risk of complete abortion. In later pregnancy. DEMULEN 1/50-21 is classified as Category C. First trimester: Use contraindicated due to increased risk of congenital anomalies, particularly cardiovascular defects and limb reduction defects, associated with sex hormones. Se. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.