Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
GILDESS 24 FE 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 of ethinyl estradiol and drospirenone provides contraceptive effect primarily by suppression of gonadotropins (FSH and LH), inhibition of ovulation, and alterations in cervical mucus and endometrium. Drospirenone has antimineralocorticoid activity and antiandrogenic properties.
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 in women at least 14 years old who have achieved menarche and desire contraception,Treatment of premenstrual dysphoric disorder (PMDD) in women who choose to use an oral contraceptive for contraception
Prevention of pregnancy,Treatment of moderate acne vulgaris (in females ≥15 years with no contraindications)
One tablet orally once daily for 24 days, followed by 4 days of placebo (iron tablets). The active tablets contain 0.8 mg norethindrone acetate and 0.025 mg ethinyl estradiol.
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 ~13-27 hours (mean ~17 hours); drospirenone: terminal half-life ~30-40 hours (mean ~32 hours). Clinical context: Steady-state achieved within 10 days for both components.
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 via CYP3A4; drospirenone is also metabolized via CYP3A4 and sulfation. Ethinyl estradiol undergoes first-pass metabolism and is conjugated in the gut and liver.
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.
Renal: ~50-60% as metabolites (ethinyl estradiol glucuronide and sulfate conjugates, drospirenone metabolites); fecal: ~40-50% (drospirenone metabolites); biliary excretion contributes to enterohepatic circulation.
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: ~98% bound (primarily albumin); drospirenone: ~95-97% bound (albumin and sex hormone-binding globulin, SHBG).
Levonorgestrel: 98-99% bound to sex hormone-binding globulin (SHBG) and albumin; ethinyl estradiol: 98% bound to albumin.
Ethinyl estradiol: Vd ~2-4 L/kg (extensive tissue distribution); drospirenone: Vd ~4 L/kg (distributes to tissues, including breast and reproductive organs).
Levonorgestrel: Vd ~1.8 L/kg (suggesting extensive tissue distribution). Ethinyl estradiol: Vd ~2.4 L/kg.
Oral: Ethinyl estradiol ~45-50% (first-pass metabolism); drospirenone ~76-85% (high oral bioavailability, limited first-pass effect).
Oral bioavailability: levonorgestrel ~100% (nearly complete); ethinyl estradiol ~45-50% (first-pass hepatic metabolism).
No dose adjustment required for mild to moderate renal impairment. Not studied in severe renal impairment; use with caution due to potential fluid retention and hormonal changes.
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 Child-Pugh Class B or C (moderate to severe hepatic impairment). For mild impairment (Child-Pugh A), no dose adjustment but monitor liver function.
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 postmenarcheal females less than 18 years of age. Use is generally not recommended before menarche.
Not indicated for use before menarche. For postmenarchal adolescents, same dosing as adults (1 tablet daily, 21/7 regimen) after evaluation of risks.
Not indicated for use in postmenopausal women. No specific geriatric dosing; use is not recommended in this population.
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 the risk of serious cardiovascular events from combination oral contraceptive use. This risk increases with age and with heavy smoking (15 or more cigarettes per day) and is quite marked in women over 35 years of age. Women who use combination oral contraceptives should be strongly advised not to smoke.
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 and other vascular events (e.g., myocardial infarction, stroke, venous thromboembolism),Risk for hyperkalemia in patients with renal/hepatic impairment or on medications that increase potassium,Liver disease (e.g., acute hepatitis, cholestatic jaundice),Hypertension,Carbohydrate and lipid metabolic effects,Headache (including migraine),Bleeding irregularities,Depression,Gallbladder disease,Hereditary angioedema
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.
Renal impairment (creatinine clearance <30 m L/min),Adrenal insufficiency,High risk of arterial/venous thrombotic events,Current or history of breast cancer or other estrogen-sensitive cancer,Liver tumors or active liver disease,Undiagnosed abnormal uterine bleeding,Pregnancy,Hypersensitivity to any component
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. Grapefruit juice may increase estrogen levels, but clinical significance is low. Avoid St. John's wort as it can reduce contraceptive efficacy.
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. First trimester: Increased risk of congenital anomalies (cardiovascular defects, neural tube defects) from estrogen/progestin exposure. Second/third trimester: No direct fetal toxicity reported. Postpartum: Excreted in breast milk, but no adverse effects documented.
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.
Safety category L3 (moderately safe). Ethinyl estradiol levels in milk: 0.8-1.5 ng/m L; M/P ratio ~0.3. Levonorgestrel levels: 0.5-1.0 ng/m L; M/P ratio ~0.4. Theoretical risk of estrogenic effects in infant; use alternative contraception if possible.
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 required as drug should be discontinued immediately if pregnancy occurs. Pharmacokinetic changes (e.g., increased hepatic clearance, plasma volume expansion) are irrelevant due to contraindication.
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 24 FE is a combined oral contraceptive containing ethinyl estradiol and desogestrel. Iron supplementation (ferrous fumarate) in the placebo pills may cause constipation or black stools. Monitor for thromboembolic events, especially in smokers over 35. Efficacy may be reduced with enzyme-inducing drugs. Missed pill protocol: if missed one active pill, take as soon as remembered; if missed two or more, take last missed pill and use backup contraception for 7 days.
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 if not sexually active.,If you miss a pill, refer to the package insert for instructions; use backup contraception if needed.,Iron pills in the placebo week may cause dark stools or constipation; inform your doctor if symptoms persist.,Do not smoke while taking this medication, especially if over 35, due to increased risk of blood clots.,Common side effects include nausea, breast tenderness, and breakthrough bleeding; these often improve after 3 months.,Seek immediate medical attention for signs of blood clot: leg pain/swelling, sudden chest pain, shortness of breath, or severe headache.
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 24 FE vs ALTAVERA, answered by our medical review team.
GILDESS 24 FE is a Oral Contraceptive that works by Combination of ethinyl estradiol and drospirenone provides contraceptive effect primarily by suppression of gonadotropins (FSH and LH), inhibition of ovulation, and alterations in cervical mucus and endometrium. Drospirenone has antimineralocorticoid activity and antiandrogenic properties.. 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 24 FE 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 24 FE is: One tablet orally once daily for 24 days, followed by 4 days of placebo (iron tablets). The active tablets contain 0.8 mg norethindrone acetate and 0.025 mg ethinyl estradiol.. 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 24 FE 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 24 FE is classified as Category C. FDA Pregnancy Category X. Contraindicated in pregnancy. First trimester: Increased risk of congenital anomalies (cardiovascular defects, neural tube defects) from estrogen/progesti. 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.