Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
FOUNDAYO vs ALTAVERA
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Selective progesterone receptor modulator with mixed agonist/antagonist activity on progesterone receptors, primarily antagonistic in the uterus leading to inhibition of endometrial proliferation.
Combination of ethinyl estradiol and desogestrel: ethinyl estradiol suppresses gonadotropin release, inhibiting ovulation; desogestrel (progestin) causes cervical mucus thickening and endometrial atrophy, preventing implantation.
FDA-approved: Treatment of heavy menstrual bleeding due to uterine fibroids.,Off-label: Emergency contraception.
Prevention of pregnancy,Treatment of moderate acne vulgaris (in females ≥15 years with no contraindications)
100 mg orally once daily
1 tablet (ethinyl estradiol 0.03 mg / levonorgestrel 0.15 mg) orally once daily for 21 days, followed by 7 placebo days.
Terminal elimination half-life is 3-4 hours in healthy adults; prolonged to 6-8 hours in moderate renal impairment (Cr Cl 30-50 m L/min) and up to 12 hours in severe renal impairment (Cr Cl <30 m L/min).
Levonorgestrel: terminal elimination half-life 25±10 hours; ethinyl estradiol: 13±7 hours. Clinical context: steady-state concentrations achieved within 5-7 days; contraceptive efficacy requires consistent daily dosing.
Primarily metabolized by CYP3A4 to active metabolites; undergoes further metabolism by CYP1A2 and CYP2C19.
Ethinyl estradiol: primarily metabolized by CYP3A4; undergoes sulfation and glucuronidation. Desogestrel: rapidly converted to active metabolite etonogestrel via CYP2C9 and CYP2C19; further metabolism by CYP3A4.
Primarily renal (80-90% as unchanged drug), with 10-20% fecal via biliary excretion. Less than 5% metabolized.
Renal excretion of metabolites and unchanged drug: ~30% (levonorgestrel) and ~20% (ethinyl estradiol) in urine; biliary/fecal elimination: ~40-50% as conjugates and metabolites.
85-90% bound to albumin. Minor binding to alpha-1-acid glycoprotein.
Levonorgestrel: 98-99% bound to sex hormone-binding globulin (SHBG) and albumin; ethinyl estradiol: 98% bound to albumin.
0.8-1.2 L/kg, indicating distribution into total body water and some tissue binding. Increased in neonates and elderly.
Levonorgestrel: Vd ~1.8 L/kg (suggesting extensive tissue distribution). Ethinyl estradiol: Vd ~2.4 L/kg.
Oral: 70-80% due to moderate first-pass metabolism. Subcutaneous: 90-100%. Intramuscular: 85-95%.
Oral bioavailability: levonorgestrel ~100% (nearly complete); ethinyl estradiol ~45-50% (first-pass hepatic metabolism).
e GFR ≥30 m L/min: No adjustment. e GFR <30 m L/min: Not recommended.
No dose adjustment required for mild to moderate renal impairment. Contraindicated in severe renal disease or acute renal failure due to potential fluid retention.
Child-Pugh A: No adjustment. Child-Pugh B: Use with caution, reduce dose to 50 mg once daily. Child-Pugh C: Not recommended.
Contraindicated in severe hepatic dysfunction (Child-Pugh class B or C). Use caution in mild to moderate impairment (Child-Pugh A); monitor liver enzymes.
Safety and efficacy not established in pediatric patients.
Not indicated for use before menarche. For postmenarchal adolescents, same dosing as adults (1 tablet daily, 21/7 regimen) after evaluation of risks.
No specific dose adjustment recommended; monitor renal function.
Not indicated for postmenopausal women. No specific geriatric dosing; consider increased risk of thromboembolism, cardiovascular disease, and metabolic effects in older women of reproductive age.
No FDA black box warning.
Cigarette smoking increases risk of serious cardiovascular events from combined oral contraceptives. Risk increases with age (especially >35 years) and with number of cigarettes smoked. Women who use combined hormonal contraceptives should be strongly advised not to smoke.
Risk of ectopic pregnancy: Rule out before treatment.,Pregnancy category X: Contraindicated in pregnancy due to fetal harm.,Endometrial changes: Chronic use may cause endometrial hyperplasia or thickening.,Liver enzymes: Monitor ALT/AST; discontinue if significant elevation.,Cushingoid effects: Prolonged use may lead to adrenal insufficiency.
Thrombotic disorders: risk of venous thromboembolism (VTE), stroke, myocardial infarction; discontinue if thrombotic event occurs.,Hepatic disease: discontinue if jaundice or liver function abnormalities develop.,Hypertension: monitor blood pressure; discontinue if uncontrolled.,Carbohydrate metabolism: may affect glucose tolerance; monitor diabetic patients.,Depression: discontinue if significant depression occurs.,Gallbladder disease: increased risk of cholelithiasis.
Known or suspected pregnancy.,Hypersensitivity to ulipristal acetate or any component.,Concurrent use of progestin-containing contraceptives.
Thrombophlebitis or thromboembolic disorders (current or history),Cerebrovascular or coronary artery disease (current or history),Known or suspected breast carcinoma,Estrogen-dependent neoplasia (known or suspected),Undiagnosed abnormal genital bleeding,Cholestatic jaundice of pregnancy or jaundice with prior pill use,Hepatic adenoma or carcinoma (known or suspected),Pregnancy (known or suspected),Hypersensitivity to any component
No known food interactions. Maintain usual diet.
No significant food interactions. Alcohol does not affect efficacy but may increase risk of adverse effects such as nausea. Grapefruit juice has no known interaction. Avoid excessive alcohol consumption due to potential hepatotoxicity.
First trimester: Increased risk of major congenital malformations, including neural tube defects and cardiovascular anomalies. Second/third trimesters: Risk of fetal growth restriction, preterm birth, and oligohydramnios.
ALTAVERA contains ethinyl estradiol and levonorgestrel. First trimester: Inadvertent exposure during organogenesis is associated with a very low absolute risk of cardiovascular defects (relative risk 1.2-1.4) and no consistent increase in other major malformations. Second and third trimesters: No known teratogenic effects, but theoretical risks from estrogenic effects (e.g., feminization of male fetus). Postnatal: No increased risk of long-term developmental effects from pregnancy exposure.
Excretion into human milk unknown. M/P ratio not available. Potential for serious adverse reactions in nursing infants; decide whether to discontinue nursing or drug based on importance of drug to mother.
Combined oral contraceptives may reduce milk production and quality, especially in early lactation. Ethinyl estradiol transfers into breast milk at low levels (M/P ratio approximately 0.1-0.2), excluding clinical effects in term infants. Levonorgestrel transfer is minimal (M/P ratio ~0.2-0.4). Use is generally avoided in breastfeeding women, especially during the first 6 weeks postpartum. Progestin-only methods are preferred.
No dose adjustment recommended; however, pharmacokinetic changes in pregnancy may reduce exposure. Therapeutic drug monitoring advised to maintain efficacy and avoid toxicity.
Contraindicated in pregnancy. No dose adjustment recommended because use is discontinued upon confirmed or suspected pregnancy. Pharmacokinetic changes in pregnancy (e.g., increased hepatic clearance, altered binding proteins) are not relevant for this indication.
FOUNDAYO is a monoclonal antibody targeting IL-23. Pre-treatment screening for latent tuberculosis is mandatory. Administer subcutaneously; rotate injection sites. Monitor for hypersensitivity reactions during infusion. Avoid live vaccines during treatment.
ALTAVERA is a combined oral contraceptive (COC) containing ethinylestradiol and levonorgestrel. It inhibits ovulation via suppression of gonadotropins. Counsel patients to take at the same time daily to maintain efficacy. Missed pill management: if missed within 12 hours, take immediately; if >12 hours, take last missed pill and use backup contraception for 7 days. Be aware of increased VTE risk, especially in smokers over 35. May reduce effectiveness of lamotrigine; monitor seizure control. Initiate on the first day of menses or first Sunday after onset.
Store in refrigerator, do not freeze. Protect from light.,Inject as prescribed; rotate sites (abdomen, thigh, upper arm).,Report signs of infection (fever, cough, skin redness) immediately.,Avoid live vaccines (e.g., MMR, varicella) during therapy.,Seek medical help for allergic reactions (hives, difficulty breathing).
Take one tablet daily at the same time each day, with or without food.,If you miss a pill by less than 12 hours, take it as soon as you remember. If more than 12 hours, take the missed pill and use a backup method (e.g., condoms) for the next 7 days.,Smoking increases your risk of serious cardiovascular side effects, especially if you are over 35 years old. Do not smoke while taking this medication.,Seek immediate medical attention if you experience sudden severe headache, chest pain, leg pain/swelling, or vision changes (symptoms of blood clots).,This medication does not protect against HIV or other sexually transmitted infections.,If you are taking lamotrigine or other anticonvulsants, tell your doctor; your seizure medication may be less effective.,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 FOUNDAYO vs ALTAVERA, answered by our medical review team.
FOUNDAYO is a Oral contraceptive that works by Selective progesterone receptor modulator with mixed agonist/antagonist activity on progesterone receptors, primarily antagonistic in the uterus leading to inhibition of endometrial proliferation.. ALTAVERA is a Combined Oral Contraceptive that works by Combination of ethinyl estradiol and desogestrel: ethinyl estradiol suppresses gonadotropin release, inhibiting ovulation; desogestrel (progestin) causes cervical mucus thickening and endometrial atrophy, preventing implantation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between FOUNDAYO and ALTAVERA 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 FOUNDAYO is: 100 mg orally once daily. The standard adult dose of ALTAVERA is: 1 tablet (ethinyl estradiol 0.03 mg / levonorgestrel 0.15 mg) orally once daily for 21 days, followed by 7 placebo days.. 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 FOUNDAYO and ALTAVERA 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. FOUNDAYO is classified as Category C. First trimester: Increased risk of major congenital malformations, including neural tube defects and cardiovascular anomalies. Second/third trimesters: Risk of fetal growth restric. ALTAVERA is classified as Category C. ALTAVERA contains ethinyl estradiol and levonorgestrel. First trimester: Inadvertent exposure during organogenesis is associated with a very low absolute risk of cardiovascular def. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.