Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
GENCEPT 10/11-28 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 ethinyl estradiol (estrogen) and levonorgestrel (progestin) inhibits ovulation by suppressing gonadotropin release, increases cervical mucus viscosity to impede sperm penetration, and alters 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.
Female contraception
Prevention of pregnancy
One tablet (ethinyl estradiol 0.01 mg/levonorgestrel 0.1 mg) orally once daily for 28 days. For the first 21 days, active tablets are taken; the next 7 days are 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.
Terminal elimination half-life is approximately 8-12 hours. Steady state is achieved within 2-3 days.
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 CYP3A4; Levonorgestrel: CYP3A4, undergoes reduction and sulfation.
Ethinyl estradiol: primarily hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Renal excretion accounts for approximately 70% of elimination (as unchanged drug and metabolites), with about 10% biliary/fecal. The remaining is metabolized.
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%).
98% bound to serum proteins, primarily albumin and alpha-1-acid glycoprotein.
Norethindrone: 61% bound to albumin and SHBG; ethinyl estradiol: 97-98% bound to albumin.
Volume of distribution is approximately 0.8-1.0 L/kg, indicating extensive tissue distribution.
Norethindrone: 3.8-4.5 L/kg; ethinyl estradiol: 2.0-4.0 L/kg. Large Vd indicates extensive tissue distribution.
Oral bioavailability is approximately 90%, with minimal first-pass metabolism.
Oral: Norethindrone ~64%, ethinyl estradiol ~38-48% (due to first-pass metabolism).
No dose adjustment required for mild to moderate renal impairment. In severe renal impairment (GFR <30 m L/min), use with caution due to potential 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 patients with Child-Pugh class B or C hepatic impairment (moderate to severe). In mild hepatic impairment (Child-Pugh class A), use with caution due to altered hormone metabolism.
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 before menarche. For post-menarche adolescents, follow same dosing as adults.
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 women above 55 years of age due to increased risk of thromboembolic events and lack of efficacy data.
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. Women over 35 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 (thrombophlebitis, pulmonary embolism, stroke, MI),Visual abnormalities (retinal thrombosis, papilledema),Hepatic neoplasia (benign/malignant liver tumors),Hypertension,Glucose intolerance/diabetes,Gallbladder disease,Depression,Bleeding irregularities
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,Cholestatic jaundice of pregnancy or jaundice with prior pill use,Hepatic adenoma or carcinoma,Known or suspected pregnancy,Hypersensitivity to any component
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 interactions are known. However, grapefruit juice may increase ethinyl estradiol levels; consider limiting grapefruit juice intake. Avoid excessive alcohol, as it may increase liver toxicity risk.
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.
GENCEPT 10/11-28 contains gestodene and ethinylestradiol. Gestodene is a progestogen; ethinylestradiol is an estrogen. Combined hormonal contraceptives are contraindicated in pregnancy. First trimester: no increased risk of major birth defects based on epidemiological studies, but should not be used once pregnancy is confirmed. Second and third trimesters: no therapeutic indication; animal studies show fetotoxicity at high doses. Overall, use is not recommended in pregnancy.
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).
Gestodene and ethinylestradiol are excreted in breast milk in small amounts. The M/P ratio for ethinylestradiol is approximately 0.02; for gestodene, it is unknown but likely low. Combined hormonal contraceptives may reduce milk production and composition, especially in early lactation; use is generally not recommended during breastfeeding, particularly in the first 6 months postpartum. Progestin-only alternatives are preferred.
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 is applicable as the drug is contraindicated in pregnancy. Pharmacokinetic changes in pregnancy (increased volume of distribution, altered hepatic metabolism) would theoretically reduce ethinylestradiol and gestodene levels, but since the drug is not used in pregnancy, no dosing recommendations are made.
Contraindicated in pregnancy; no dose adjustments applicable. Discontinue medication immediately upon pregnancy detection.
GENCEPT 10/11-28 is a combination oral contraceptive containing ethinyl estradiol 10 mcg and drospirenone 3 mg (24 active tablets) plus placebo (4 tablets). It is used for contraception and treatment of moderate acne vulgaris in women who desire oral contraception. The 24-day active regimen increases ovarian suppression and reduces breakthrough bleeding. Drospirenone has antimineralocorticoid activity, which may cause hyperkalemia in patients with renal impairment, hepatic disease, or adrenal insufficiency. Monitor potassium in at-risk patients. Do not use with other potassium-sparing drugs. Avoid in women with hypertension, diabetes with vascular disease, or migraine with aura due to increased cardiovascular risk with low-dose EE. Consider starting on first day of menses for immediate contraceptive effect.
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 pill daily at the same time, in the order shown on the pack. Do not skip pills.,Use backup contraception (e.g., condoms) if you miss a pill, vomit within 3-4 hours after taking a pill, or have severe diarrhea.,Contact your doctor immediately if you experience leg pain, chest pain, shortness of breath, severe headache, vision changes, or jaundice.,Cigarette smoking increases the risk of serious cardiovascular side effects. Do not smoke while taking this medication.,Store at room temperature, away from moisture and heat.
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 GENCEPT 10/11-28 vs ALYACEN 1/35, answered by our medical review team.
GENCEPT 10/11-28 is a Oral Contraceptive that works by Combination of ethinyl estradiol (estrogen) and levonorgestrel (progestin) inhibits ovulation by suppressing gonadotropin release, increases cervical mucus viscosity to impede sperm penetration, and alters 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 GENCEPT 10/11-28 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 GENCEPT 10/11-28 is: One tablet (ethinyl estradiol 0.01 mg/levonorgestrel 0.1 mg) orally once daily for 28 days. For the first 21 days, active tablets are taken; the next 7 days are 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 GENCEPT 10/11-28 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. GENCEPT 10/11-28 is classified as Category C. GENCEPT 10/11-28 contains gestodene and ethinylestradiol. Gestodene is a progestogen; ethinylestradiol is an estrogen. Combined hormonal contraceptives are contraindicated in pregn. 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.