Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
GILDESS FE 1.5/30 vs ALYACEN 1/35
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 (estrogen) and levonorgestrel (progestin) suppress gonadotropin secretion (FSH and LH) via negative feedback, inhibiting ovulation, increasing cervical mucus viscosity, and altering endometrial receptivity.
Combination hormonal contraceptive: ethinyl estradiol suppresses gonadotropin release via negative feedback on hypothalamic-pituitary axis; norethindrone induces progestational effects including cervical mucus thickening and endometrial changes, inhibiting ovulation and sperm penetration.
Prevention of pregnancy
Prevention of pregnancy
One tablet orally once daily at the same time each day for 21 consecutive days, followed by 7 days of placebo tablets.
One tablet (norethindrone 1 mg and ethinyl estradiol 35 mcg) orally once daily for 21 consecutive days, followed by 7 days of placebo or no tablets.
Ethinyl estradiol: terminal elimination half-life approximately 13-27 hours (mean ~17 hours); clinical context: supports daily dosing with steady state achieved in ~1 week. Gestodene: terminal elimination half-life approximately 12-15 hours; clinical context: allows for maintaining stable serum concentrations with once-daily dosing.
Norethindrone: 8-11 hours (terminal); ethinyl estradiol: 10-20 hours (terminal). The half-life supports once-daily dosing for oral contraceptive efficacy.
Ethinyl estradiol: primarily metabolized by CYP3A4; undergoes conjugation (glucuronidation and sulfation). Levonorgestrel: metabolized by reduction and conjugation; CYP3A4 involved.
Ethinyl estradiol: primarily hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Ethinyl estradiol (EE) is primarily excreted in urine (40-45%) and feces (40-45%) as glucuronide and sulfate conjugates; less than 8% is excreted unchanged. Gestodene is extensively metabolized; its metabolites are excreted in urine (50-60%) and feces (30-40%), with less than 1% unchanged.
Renal excretion of metabolites (primarily ethinyl estradiol and norethindrone conjugates) accounts for approximately 50-60% of elimination; fecal excretion accounts for 30-40%. Unchanged drug excretion is minimal (<5%).
Ethinyl estradiol: 97-98% bound to albumin; gestodene: 65-75% bound to sex hormone-binding globulin (SHBG) and 25-35% bound to albumin; total binding ~99%.
Norethindrone: 61% bound to albumin and SHBG; ethinyl estradiol: 97-98% bound to albumin.
Ethinyl estradiol: apparent Vd ~2.5-4.0 L/kg (mean ~3 L/kg); indicates extensive tissue distribution beyond plasma volume. Gestodene: apparent Vd ~0.7-1.0 L/kg; suggests moderate distribution to tissues.
Norethindrone: 3.8-4.5 L/kg; ethinyl estradiol: 2.0-4.0 L/kg. Large Vd indicates extensive tissue distribution.
Ethinyl estradiol: oral bioavailability approximately 40-45% due to first-pass metabolism (sulfation and glucuronidation in gut wall and liver); interindividual variability significant. Gestodene: oral bioavailability nearly 100% (99-100%) due to minimal first-pass metabolism; high and consistent absorption.
Oral: Norethindrone ~64%, ethinyl estradiol ~38-48% (due to first-pass metabolism).
No dose adjustment required for mild to moderate renal impairment. Contraindicated in severe renal impairment (e GFR <30 m L/min/1.73 m²) due to potential estrogen-related fluid retention and hypertension.
No dose adjustment required for mild to moderate renal impairment. Contraindicated in severe renal impairment or acute renal failure due to potential fluid retention and electrolyte disturbances.
Contraindicated in Child-Pugh class B and C (moderate to severe hepatic impairment). Use with caution in Child-Pugh class A; closely monitor liver function.
Contraindicated in patients with hepatic impairment, including Child-Pugh class B or C, due to impaired metabolism of estrogen and progestin. Not recommended in patients with active liver disease or history of liver tumors.
Not indicated for use before menarche. Post-menarche: same as adult dosing; one tablet orally once daily.
Not indicated for use before menarche. For postmenarchal adolescents, same dosing as adults. Safety and efficacy established for contraception; weight-based dosing not applicable.
Not indicated for use in postmenopausal women due to lack of efficacy for contraception and potential increased thromboembolic risk.
Not indicated for use after menopause due to lack of benefit and increased risks (e.g., cardiovascular, thromboembolic events). If used, monitor for fluid retention, hypertension, and glucose intolerance.
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptive use. Risk increases with age (especially >35 years) and number of cigarettes smoked. Women >35 years who smoke should not use this product.
Cigarette smoking increases risk of serious cardiovascular events from combined oral contraceptives. Risk increases with age and heavy smoking (≥15 cigarettes/day). Women over 35 who smoke should not use this product.
Thrombotic disorders (venous thromboembolism, arterial thromboembolism, stroke, myocardial infarction),Carcinoma of the breast and reproductive organs,Hepatic neoplasia,Gallbladder disease,Carbohydrate and lipid metabolism effects,Elevated blood pressure,Headache,Bleeding irregularities,Ocular lesions (e.g., retinal thrombosis),Depression
Thrombotic disorders (e.g., DVT, PE, stroke, MI),Cerebrovascular disease,Hepatic neoplasia,Gallbladder disease,Hypertension,Carbohydrate and lipid effects,Ocular lesions,Hereditary angioedema,Chloasma,Menstrual irregularities,Pregnancy exclusion prior to initiation
Thrombophlebitis or thromboembolic disorders,Cerebrovascular or coronary artery disease,Known or suspected breast cancer,Estrogen-dependent neoplasia,Undiagnosed abnormal genital bleeding,Pregnancy,Benign or malignant liver tumor,Hepatic impairment,Hypersensitivity to components,Women >35 years who smoke
Venous or arterial thrombotic/thromboembolic disease (current or history),Cerebrovascular disease,Coronary artery disease,Known or suspected breast cancer,Endometrial or other estrogen-dependent neoplasia,Undiagnosed abnormal genital bleeding,Cholestatic jaundice of pregnancy or jaundice with prior pill use,Hepatic adenoma or carcinoma,Known or suspected pregnancy,Hypersensitivity to any component,Smoking in women over 35
No significant food interactions. Grapefruit juice may slightly increase ethinyl estradiol levels but not clinically relevant. The iron component may cause gastrointestinal discomfort; taking with food can reduce this, but avoid taking with dairy (calcium) or caffeine as they may reduce iron absorption. Iron tablets should be taken with water or vitamin C source to enhance absorption, but not with tea, coffee, or milk.
No significant food interactions. Grapefruit juice may increase estrogen levels, but clinically not a concern. Avoid excessive alcohol, which may impair liver function and increase estrogen exposure. Maintain a healthy diet, as weight gain is possible.
Pregnancy category X. Use contraindicated in pregnancy due to estrogenic effects on fetal development. First trimester: increased risk of congenital anomalies (cardiovascular, limb defects). Second and third trimesters: potential for fetal harm, including jaundice and liver dysfunction.
Pregnancy category X. Use of ALYACEN 1/35 (norethindrone/ethinyl estradiol) is contraindicated during pregnancy. First trimester: Increased risk of congenital anomalies, including cardiovascular defects and limb reduction defects. Second/third trimesters: Potential for urogenital abnormalities and feminization of male fetus. Exposure is associated with subsequent development of clear cell adenocarcinoma of vagina/cervix in female offspring (DES-related).
Contraindicated in breastfeeding. Estrogen and progestin components reduce milk production and quality. Limited data; M/P ratio not established. Alternative contraception recommended.
Small amounts of contraceptive steroids and/or metabolites have been identified in breast milk. M/P ratio: Not specifically determined for this combination; ethinyl estradiol M/P ratio ~0.02-0.04. Use may reduce milk production and quality. Breastfeeding not recommended during use. Alternative contraception advised.
No dose adjustment due to contraindication in pregnancy. Pharmacokinetic changes in pregnancy (increased clearance) are not applicable as drug is not used.
Contraindicated in pregnancy; no dose adjustments applicable. Discontinue medication immediately upon pregnancy detection.
GILDESS FE 1.5/30 is a combination oral contraceptive containing ethinyl estradiol 30 mcg and gestodene 1.5 mg. Gestodene is a third-generation progestin with high progestational activity and minimal androgenic effects. The iron component (ferrous fumarate) is included to counteract menstrual blood loss. This formulation is associated with a lower risk of venous thromboembolism compared to second-generation pills but still carries a risk, particularly in smokers over 35. It should be taken at the same time daily to maintain efficacy. Breakthrough bleeding is common in the first few cycles; if persistent, rule out other causes. The iron tablets are not for contraceptive use and should be taken daily during the placebo week.
ALYACEN 1/35 is a combination oral contraceptive containing ethinyl estradiol 35 mcg and norgestimate 1 mg. It is indicated for the prevention of pregnancy and for the treatment of moderate acne vulgaris in females ≥15 years of age who desire an oral contraceptive. Monitor for thromboembolic events, especially in smokers over 35 or those with migraine with aura. Use with caution in patients with liver impairment or history of cholestatic jaundice. The pill-free interval should not exceed 7 days; missed pills increase ovulation risk. Consider non-hormonal backup if vomiting or diarrhea occurs within 4 hours of dosing.
Take one tablet daily at the same time, preferably after an evening meal to minimize nausea.,If you miss a dose, follow the package instructions: if missed by less than 12 hours, take it immediately; if more than 12 hours, take the last missed pill and use backup contraception for 7 days.,Use additional barrier contraception for the first 7 days of starting the pill, or if starting after day 5 of cycle, for the first cycle.,Smoking increases the 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 symptoms of a blood clot: sudden leg pain/swelling, chest pain, shortness of breath, or sudden severe headache.,The iron tablets are not for contraception; they help replace iron lost during menstruation.,Do not use this medication if you are pregnant, have a history of blood clots, certain migraines, liver disease, or hormone-sensitive cancer.,Antibiotics (except rifampin) generally do not affect efficacy, but always consult your doctor if you are prescribed any new medication.
Take one tablet daily at the same time each day; do not skip doses.,Use an additional non-hormonal contraceptive (e.g., condoms) if you miss a pill, have vomiting, or diarrhea.,Smoking while on this pill increases the risk of blood clots and stroke, especially if you are over 35.,Contact your healthcare provider immediately if you have chest pain, leg pain/swelling, sudden vision changes, or severe headache.,This medication does not protect against HIV or other sexually transmitted infections.,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 1.5/30 vs ALYACEN 1/35, answered by our medical review team.
GILDESS FE 1.5/30 is a Oral Contraceptive that works by Combination oral contraceptive: ethinyl estradiol (estrogen) and levonorgestrel (progestin) suppress gonadotropin secretion (FSH and LH) via negative feedback, inhibiting ovulation, increasing cervical mucus viscosity, and altering endometrial receptivity.. ALYACEN 1/35 is a Oral Contraceptive that works by Combination hormonal contraceptive: ethinyl estradiol suppresses gonadotropin release via negative feedback on hypothalamic-pituitary axis; norethindrone induces progestational effects including cervical mucus thickening and endometrial changes, inhibiting ovulation and sperm penetration.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between GILDESS FE 1.5/30 and ALYACEN 1/35 depend on the specific clinical indication. These are both 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 GILDESS FE 1.5/30 is: One tablet orally once daily at the same time each day for 21 consecutive days, followed by 7 days of placebo tablets.. The standard adult dose of ALYACEN 1/35 is: One tablet (norethindrone 1 mg and ethinyl estradiol 35 mcg) orally once daily for 21 consecutive days, followed by 7 days of placebo or no tablets.. 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 1.5/30 and ALYACEN 1/35 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 1.5/30 is classified as Category C. Pregnancy category X. Use contraindicated in pregnancy due to estrogenic effects on fetal development. First trimester: increased risk of congenital anomalies (cardiovascular, limb. ALYACEN 1/35 is classified as Category C. Pregnancy category X. Use of ALYACEN 1/35 (norethindrone/ethinyl estradiol) is contraindicated during pregnancy. First trimester: Increased risk of congenital anomalies, including . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.