Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
GILDESS FE 1/20 vs ALTAVERA
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: ethinyl estradiol suppresses gonadotropin release; norethindrone induces progestational changes in endometrium and cervical mucus, preventing ovulation and fertilization.
Combination of ethinyl estradiol and desogestrel: ethinyl estradiol suppresses gonadotropin release, inhibiting ovulation; desogestrel (progestin) causes cervical mucus thickening and endometrial atrophy, preventing implantation.
Prevention of pregnancy,Treatment of moderate acne vulgaris (for females ≥15 years old who have menarche and desire contraception),Oral contraceptive for women with iron deficiency anemia (as Gildess Fe 1/20 contains ferrous fumarate)
Prevention of pregnancy,Treatment of moderate acne vulgaris (in females ≥15 years with no contraindications)
One tablet orally once daily for 21 days followed by 7 placebo tablets per 28-day cycle.
1 tablet (ethinyl estradiol 0.03 mg / levonorgestrel 0.15 mg) orally once daily for 21 days, followed by 7 placebo days.
Ethinyl estradiol: terminal half-life approximately 13 hours (range 10-15 h). Desogestrel: metabolized to etonogestrel; etonogestrel terminal half-life about 28 hours (range 20-40 h). Clinical context: steady-state reached within 7-10 days.
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.
Ethinyl estradiol undergoes CYP3A4-mediated hydroxylation; norethindrone is reduced and conjugated via glucuronidation and sulfation.
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.
Approximately 60-65% renal (as metabolites), 30-35% fecal (as metabolites and unchanged drug). Ethinyl estradiol and desogestrel metabolites are excreted primarily via urine and feces. Etonogestrel (active metabolite) is excreted mainly via feces (40%) and urine (32%).
Renal excretion of metabolites and unchanged drug: ~30% (levonorgestrel) and ~20% (ethinyl estradiol) in urine; biliary/fecal elimination: ~40-50% as conjugates and metabolites.
Ethinyl estradiol: 97-98% bound to albumin, with specific binding to sex hormone-binding globulin (SHBG). Etonogestrel: >95% bound, primarily to albumin (60-70%) and SHBG (30-40%).
Levonorgestrel: 98-99% bound to sex hormone-binding globulin (SHBG) and albumin; ethinyl estradiol: 98% bound to albumin.
Ethinyl estradiol: apparent Vd approximately 2.5 L/kg (range 2.1-3.0 L/kg). Desogestrel: Vd for etonogestrel is about 2.0 L/kg. High Vd indicates extensive tissue distribution, including adipose and reproductive tissues.
Levonorgestrel: Vd ~1.8 L/kg (suggesting extensive tissue distribution). Ethinyl estradiol: Vd ~2.4 L/kg.
Oral: Ethinyl estradiol bioavailability approximately 45-55% due to first-pass metabolism (sulfation and glucuronidation). Desogestrel: prodrug, bioavailability of etonogestrel is about 76-84% after oral dose. No other relevant routes.
Oral bioavailability: levonorgestrel ~100% (nearly complete); ethinyl estradiol ~45-50% (first-pass hepatic metabolism).
No dose adjustment required for mild to moderate renal impairment. Contraindicated in severe renal impairment (Cr Cl <30 m L/min) due to potential for fluid retention.
No dose adjustment required for mild to moderate renal impairment. Contraindicated in severe renal disease or acute renal failure due to potential fluid retention.
Contraindicated in severe hepatic impairment (Child-Pugh class C). Caution in moderate impairment (Child-Pugh class B) due to altered hormone metabolism; use alternative methods if possible.
Contraindicated in severe hepatic dysfunction (Child-Pugh class B or C). Use caution in mild to moderate impairment (Child-Pugh A); monitor liver enzymes.
Approved for postmenarchal adolescents; dosing same as adults: one tablet orally once daily for 21 days followed by 7 placebo tablets.
Not indicated for use before menarche. For postmenarchal adolescents, same dosing as adults (1 tablet daily, 21/7 regimen) after evaluation of risks.
Not typically indicated for postmenopausal women due to ineffectiveness; if used in appropriate patients, no dose adjustment required but monitor for thromboembolic risks.
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.
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptives. Risk increases with age and smoking intensity (≥15 cigarettes/day) and is significant in women >35 years old. Women >35 who smoke should not use this product.
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.
Thrombotic disorders (thrombophlebitis, venous thromboembolism, stroke, MI),Carcinoma of the breast and reproductive organs,Hepatic disease (adenoma, hepatocellular carcinoma),Ocular lesions (retinal thrombosis),Gallbladder disease,Carbohydrate and lipid effects,Elevated blood pressure,Headache/migraine,Bleeding irregularities,Depression,Hereditary angioedema,Chloasma,Hepatic function impairment,Iron supplementation (Fe fumarate): may cause GI upset, constipation, and dark stools
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.
Thrombophlebitis or thromboembolic disorders,Cerebrovascular or coronary artery disease,Known or suspected breast carcinoma,Endometrial or other estrogen-dependent neoplasia,Undiagnosed abnormal genital bleeding,Pregnancy or suspected pregnancy,Benign or malignant liver tumor,Active liver disease,Hypersensitivity to any component,Smoking in women >35 years
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 significant food interactions. However, grapefruit juice may inhibit CYP3A4 metabolism and theoretically increase estrogen levels, but clinical significance is undetermined. Avoid St. John's wort, which reduces contraceptive efficacy. Caffeine metabolism may be decreased, leading to increased caffeine effects. No specific dietary restrictions required.
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.
FDA Pregnancy Category X. Contraindicated in pregnancy due to risk of fetal harm. First trimester: Increased risk of neural tube defects, congenital heart defects, and limb reduction defects from progestin component. Second and third trimesters: Risk of fetal feminization (masculinization of female fetuses) from androgen-like effects of progestin; also associated with increased risk of neonatal hepatoblastoma and possibly other tumors. Combination hormonal contraceptives should be discontinued immediately if pregnancy occurs.
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.
Excreted in breast milk in small amounts (estrogen and progestin). M/P ratio not well-defined. Use may reduce milk production and quality, especially in early postpartum period. Consider alternative contraception during breastfeeding, especially in first 6 months. Use only if benefits outweigh risks, with close monitoring of infant growth and development.
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.
Contraindicated in pregnancy; no dose adjustments indicated as use is not recommended. If inadvertently taken during pregnancy, discontinue immediately. No dosage changes are suggested for postpartum use, but alternative contraception should be considered during breastfeeding.
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.
Gildess FE 1/20 is a monophasic oral contraceptive containing 20 mcg ethinyl estradiol and 1 mg norethindrone acetate with ferrous fumarate placebos. It is indicated for contraception and may be used off-label for acne. The low estrogen dose may lead to more breakthrough bleeding, especially in the first few cycles. Advise patients to take at the same time daily and not to skip active pills. The iron in placebos can cause dark stools; warn patients. Missed pill management: if one active pill is missed, take it as soon as remembered; if two are missed, take two and use backup contraception for 7 days. Consider CYP3A4 inducers (e.g., rifampin, certain anticonvulsants) which reduce efficacy. Not recommended in patients with BMI > 35 due to increased failure risk. Do not use in smokers over 35 years old. Monitor blood pressure and for thrombotic events.
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.
Take one pill daily at the same time, even during withdrawal bleed weeks.,If you miss a pill, follow the package instructions: take the missed pill immediately and continue; if more than one missed, use backup contraception for 7 days.,The last 7 pills in the pack are placebo; they contain iron, so do not skip them but they don't provide contraceptive protection.,Iron in placebos may cause dark stools; this is harmless.,Common side effects: nausea, breast tenderness, headache, breakthrough bleeding (especially first 3 months). These often improve with time.,Contact your doctor if you have severe abdominal pain, chest pain, shortness of breath, severe headaches, vision changes, or leg pain/swelling.,This pill does not protect against sexually transmitted infections (STIs). Use condoms for STI prevention.,Avoid smoking while taking this medication, especially if over 35 years old.,Tell your doctor about all medications, especially antibiotics, antifungals, and seizure medications, as they may decrease effectiveness.,If you are undergoing surgery, inform your surgeon you are taking this pill.
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 GILDESS FE 1/20 vs ALTAVERA, answered by our medical review team.
GILDESS FE 1/20 is a Oral Contraceptive that works by Combination oral contraceptive: ethinyl estradiol suppresses gonadotropin release; norethindrone induces progestational changes in endometrium and cervical mucus, preventing ovulation and fertilization.. 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 GILDESS FE 1/20 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 GILDESS FE 1/20 is: One tablet orally once daily for 21 days followed by 7 placebo tablets per 28-day cycle.. 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 GILDESS FE 1/20 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. GILDESS FE 1/20 is classified as Category C. FDA Pregnancy Category X. Contraindicated in pregnancy due to risk of fetal harm. First trimester: Increased risk of neural tube defects, congenital heart defects, and limb reducti. 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.