Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CYCLESSA 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) inhibits ovulation by suppressing gonadotropin release, increases viscosity of cervical mucus 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.
Prevention of pregnancy
Prevention of pregnancy
One tablet (0.15 mg desogestrel/0.02 mg ethinyl estradiol) orally once daily for 21 days, followed by 7 days of placebo.
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.
Desogestrel: 38±13 hours (terminal); ethinyl estradiol: 14±3 hours (terminal). Steady-state reached after 7-10 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 is metabolized primarily via CYP3A4; desogestrel is converted to active metabolite etonogestrel via CYP2C9 and CYP2C19.
Ethinyl estradiol: primarily hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Urine (50-60% as metabolites, <10% unchanged); feces (30-40% as metabolites); enterohepatic circulation.
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%).
Desogestrel: 99.7% (SHBG); ethinyl estradiol: 98.5% (albumin, SHBG).
Norethindrone: 61% bound to albumin and SHBG; ethinyl estradiol: 97-98% bound to albumin.
Desogestrel: 1.0-1.5 L/kg (extensive tissue distribution); ethinyl estradiol: 0.15-0.35 L/kg (limited).
Norethindrone: 3.8-4.5 L/kg; ethinyl estradiol: 2.0-4.0 L/kg. Large Vd indicates extensive tissue distribution.
Desogestrel: 76% (oral); ethinyl estradiol: 55% (oral, variable due to 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. Insufficient data for severe impairment (Cr Cl <30 m L/min); use with caution.
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 C (severe hepatic impairment). For mild to moderate (Child-Pugh A or B), use with caution: reduce estrogen dose or discontinue if intolerance occurs.
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. For postmenarchal adolescents, dose same as adults: 0.15 mg desogestrel/0.02 mg ethinyl estradiol 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 postmenopausal women. No studies in geriatric population; use not recommended due to lack of benefit and increased thromboembolic risk with age.
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 combined hormonal contraceptives. Risk increases with age and amount smoked (especially in women >35 years who smoke). Women should not use CYCLESSA if they smoke cigarettes and are over 35 years old.
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),Cerebrovascular disease,Cardiovascular disease including myocardial infarction,Liver disease including hepatic adenoma,Increased blood pressure,Gallbladder disease,Carbohydrate and lipid metabolism effects,Headache,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
Known or suspected pregnancy,Current or past breast cancer or other estrogen-sensitive cancer,Current or past deep vein thrombosis or pulmonary embolism,Current or history of thrombogenic valvular or rhythm disease,Cerebrovascular or coronary artery disease,Uncontrolled hypertension,Major surgery with prolonged immobilization,Diabetes with vascular involvement,Severe liver disease or liver tumor,Undiagnosed abnormal uterine bleeding,Age >35 years and smoking
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 estrogen levels but not clinically relevant. Alcohol does not affect efficacy but may increase risk of liver damage with high doses.
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: The use of combined hormonal contraceptives containing desogestrel and ethinyl estradiol is not associated with an increased risk of major birth defects. Discontinuation due to first-trimester exposure is not indicated. Second and third trimesters: Prolonged exposure to estrogen-progestin combinations has been associated with rare risks such as congenital heart defects and limb reduction defects in case-control studies, but absolute risk is low. Fetal risk from inadvertent use in pregnancy is minimal; termination not recommended.
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).
Small amounts of contraceptive steroids and/or metabolites have been identified in breast milk. Studies with combined oral contraceptives suggest possible effects on milk production and composition; use during lactation should be postponed until the infant is weaned or at least 6 months postpartum. M/P ratio for ethinyl estradiol and desogestrel metabolites is not well established; limited data suggest low transfer.
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 adjustments are applicable as CYCLESSA is contraindicated during pregnancy. In the event of inadvertent use, the drug should be discontinued as soon as pregnancy is confirmed. No pharmacokinetic-based dose changes are required because use is not recommended in pregnancy.
Contraindicated in pregnancy; no dose adjustments applicable. Discontinue medication immediately upon pregnancy detection.
CYCLESSA (desogestrel/ethinyl estradiol) is a monophasic oral contraceptive. It may be used off-label for acne treatment. Breakthrough bleeding is common in the first 3 cycles. CYP3A4 inducers (e.g., rifampin) reduce efficacy; consider backup contraception.
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, even if no intercourse.,Start on the first day of menstrual period or first Sunday after period starts.,Use backup contraception for first 7 days if starting after day 5.,Missed pill: take as soon as remembered. If more than 2 missed, use backup method.,Vomiting or diarrhea may reduce effectiveness.,Report unexplained leg pain, chest pain, severe headache, or vision changes.,Smoking increases risk of serious cardiovascular side effects, especially if over 35.
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 CYCLESSA vs ALYACEN 1/35, answered by our medical review team.
CYCLESSA is a Oral Contraceptive that works by Combination of estrogen (ethinyl estradiol) and progestin (desogestrel) inhibits ovulation by suppressing gonadotropin release, increases viscosity of cervical mucus 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 CYCLESSA 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 CYCLESSA is: One tablet (0.15 mg desogestrel/0.02 mg ethinyl estradiol) orally once daily for 21 days, followed by 7 days of placebo.. 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 CYCLESSA 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. CYCLESSA is classified as Category C. First trimester: The use of combined hormonal contraceptives containing desogestrel and ethinyl estradiol is not associated with an increased risk of major birth defects. Discontin. 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.