Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
GILDESS 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 of estrogen (ethinyl estradiol) and progestin (desogestrel) that inhibits gonadotropin release, suppressing ovulation, increasing cervical mucus viscosity, and altering endometrial morphology.
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.
Oral contraception
Prevention of pregnancy
One tablet orally once daily at the same time each day.
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.
Ethinylestradiol: terminal half-life 13-17 hours (mean 15 h). Desogestrel active metabolite 3-keto-desogestrel: terminal half-life 23-28 hours (mean 25 h). Clinical: steady-state achieved by cycle day 7-10; missed pill instructions based on half-life.
Norethindrone: 8-11 hours (terminal); ethinyl estradiol: 10-20 hours (terminal). The half-life supports once-daily dosing for oral contraceptive efficacy.
Ethinyl estradiol undergoes first-pass metabolism in gut wall and liver via CYP3A4; desogestrel is metabolized by CYP2C9 and CYP2C19 to active metabolite etonogestrel.
Ethinyl estradiol: primarily hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Renal: ~55-60% as ethinylestradiol glucuronide and sulfate conjugates; ~40% as desogestrel metabolites (largely as 3-keto-desogestrel glucuronide). Fecal: ~30-35% of desogestrel metabolites; <5% for ethinylestradiol. Biliary: minor for both.
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%).
Ethinylestradiol: ~97% bound to albumin (90%) and SHBG (minor). 3-Keto-desogestrel: ~95% bound: albumin (65%) and SHBG (30%).
Norethindrone: 61% bound to albumin and SHBG; ethinyl estradiol: 97-98% bound to albumin.
Ethinylestradiol: Vd ~2.5-3.0 L/kg; distributes extensively into body tissues (breast, liver). 3-Keto-desogestrel: Vd ~1.5-2.0 L/kg; moderate tissue binding.
Norethindrone: 3.8-4.5 L/kg; ethinyl estradiol: 2.0-4.0 L/kg. Large Vd indicates extensive tissue distribution.
Oral: ethinylestradiol ~40-50% (due to first-pass metabolism); desogestrel ~76% (≥60% converted to active 3-keto-desogestrel after first pass).
Oral: Norethindrone ~64%, ethinyl estradiol ~38-48% (due to first-pass metabolism).
Contraindicated in patients with renal impairment (e GFR <60 m L/min/1.73 m2) due to increased risk of hyperkalemia and reduced efficacy.
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 patients with hepatic impairment (Child-Pugh class B or C) due to impaired hormone metabolism and potential for adverse effects.
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 in pediatric patients. Safety and efficacy have not been established in females under 18 years of age.
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. Efficacy in women over 40 years of age has not been fully established; consider alternative contraception due to increased cardiovascular 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 and smoking intensity (especially in women over 35).
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.
Increased risk of thromboembolic disorders (e.g., DVT, PE),Myocardial infarction and stroke risk,Hepatic neoplasia,Gallbladder disease,Hypertension,Carbohydrate/lipid effects,Ocular lesions,Dose-related risk of VTE from desogestrel-containing pills
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,History of DVT or PE,Cerebrovascular or coronary artery disease,Known or suspected breast carcinoma,Estrogen-dependent neoplasia,Undiagnosed abnormal genital bleeding,Pregnancy,Hepatic adenoma or carcinoma,Active liver disease with abnormal function
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 specific food restrictions. Grapefruit juice does not significantly interact with ethinylestradiol or gestodene. St. John's Wort (Hypericum perforatum) reduces contraceptive efficacy by inducing CYP3A4 metabolism; avoid concurrent use. High-fat meals may increase ethinylestradiol absorption slightly but no dose adjustment needed.
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.
First trimester: Combination oral contraceptives are not associated with a major increase in risk of birth defects. Second and third trimesters: Prolonged use may be associated with fetal harm including cardiovascular and skeletal anomalies, though data are limited. Known pregnancy contraindicates use.
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).
Ethinyl estradiol and levonorgestrel are excreted in breast milk in small amounts. M/P ratio not established. Potential for adverse effects in nursing infant, including reduced milk production and jaundice. Use not recommended in breastfeeding women.
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.
Contraindicated in pregnancy. No dose adjustments applicable; use should be discontinued immediately if pregnancy occurs.
Contraindicated in pregnancy; no dose adjustments applicable. Discontinue medication immediately upon pregnancy detection.
GILDESS 1.5/30 is a combined oral contraceptive (COC) containing ethinylestradiol 30 µg and gestodene 75 µg. Gestodene is a third-generation progestin with high progestogenic activity and low androgenic effects, reducing acne and hirsutism. This formulation has a higher risk of venous thromboembolism (VTE) compared to second-generation COCs. Avoid in women with migraines with aura, hypertension (BP >160/100), or BMI >30 due to increased VTE risk. For missed pills: if one pill is missed, take it as soon as remembered and continue; if two or more pills are missed, take the last missed pill, use backup contraception for 7 days, and consider emergency contraception if unprotected intercourse occurred.
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 in the evening, to reduce nausea.,If you miss a pill, follow the instructions in the package leaflet; if you miss more than one pill, use additional contraception (e.g., condoms) for 7 days.,Smoking increases the risk of serious cardiovascular side effects; do not smoke while taking this medication, especially if you are over 35.,Tell your doctor if you experience severe headache, chest pain, leg pain or swelling, visual disturbances, or jaundice.,This medication does not protect against sexually transmitted infections; use condoms for additional protection.,Vomiting or severe diarrhea within 4 hours of taking the pill reduces efficacy; consider it as a missed pill and use backup contraception.
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 1.5/30 vs ALYACEN 1/35, answered by our medical review team.
GILDESS 1.5/30 is a Oral Contraceptive that works by Combination of estrogen (ethinyl estradiol) and progestin (desogestrel) that inhibits gonadotropin release, suppressing ovulation, increasing cervical mucus viscosity, and altering endometrial morphology.. 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 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 1.5/30 is: One tablet orally once daily at the same time each day.. 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 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 1.5/30 is classified as Category C. First trimester: Combination oral contraceptives are not associated with a major increase in risk of birth defects. Second and third trimesters: Prolonged use may be associated wit. 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.