Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
SPRINTEC 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 and norgestimate suppresses gonadotropin release, inhibiting ovulation and altering cervical mucus and endometrium to prevent pregnancy.
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,Treatment of moderate acne vulgaris in women at least 15 years of age who have achieved menarche and are seeking an oral contraceptive
Prevention of pregnancy
One tablet (0.25 mg norgestimate, 0.035 mg ethinyl estradiol) orally once daily at the same time each day for 21 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: 13 ± 3 hours (variable, influenced by CYP3A4 activity); Norgestimate: 1.5-2 hours (rapidly converted to norelgestromin); Norelgestromin: 12-20 hours (active metabolite); clinical context: dosing interval of 24 hours supports once-daily administration.
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 by CYP3A4; norgestimate is rapidly metabolized to norelgestromin and norgestrel via first-pass metabolism.
Ethinyl estradiol: primarily hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Renal: approximately 50-60% (metabolites, primarily glucuronide conjugates), Fecal: approximately 30-40% (biliary excretion of metabolites), with minimal unchanged drug in urine (<5%).
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% bound to albumin; Norgestimate/norelgestromin: 99% bound to albumin and sex hormone-binding globulin (SHBG).
Norethindrone: 61% bound to albumin and SHBG; ethinyl estradiol: 97-98% bound to albumin.
Ethinyl estradiol: 2.5-4.0 L/kg; Norgestimate: not determined (extensive tissue distribution); clinical meaning: reflects distribution into total body water and tissues.
Norethindrone: 3.8-4.5 L/kg; ethinyl estradiol: 2.0-4.0 L/kg. Large Vd indicates extensive tissue distribution.
Ethinyl estradiol: 38-48% due to first-pass metabolism; Norgestimate: 100% (prodrug, rapidly hydrolyzed in gut wall and liver).
Oral: Norethindrone ~64%, ethinyl estradiol ~38-48% (due to first-pass metabolism).
No dose adjustment required for mild to moderate renal impairment. Not studied in severe renal impairment; use 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 patients with acute or chronic hepatic dysfunction (Child-Pugh class B or C). No data for mild impairment; use with caution.
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.
Safety and efficacy have not been established in postmenarchal pediatric patients. Use after first menses; dosing same 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 postmenopausal women. No specific dose adjustment needed for elderly patients beyond contraindications.
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 oral contraceptive use. Risk increases with age (>35 years) and number of cigarettes smoked. Women over 35 who smoke should not use combined oral contraceptives.
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,Increased risk of myocardial infarction and stroke, especially in smokers,Increased risk of hepatic neoplasia,Elevated blood pressure,Gallbladder disease,Carbohydrate and lipid effects,Ocular lesions,Hereditary angioedema,Chloasma
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
Avoid grapefruit juice as it may increase estrogen levels and risk of adverse effects. No other significant food interactions are known; maintain consistent dietary habits to minimize gastrointestinal side effects.
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.
FDA Pregnancy Category X. Use contraindicated in pregnancy. First trimester: Major congenital anomalies including cardiovascular and limb defects; increased risk of neural tube defects. Second and third trimesters: Fetal genital abnormalities in females (diethylstilbestrol-like effect); potential for long-term reproductive tract changes. Postnatal: Possible increased risk of neurodevelopmental issues.
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).
Excreted in human breast milk with milk-to-plasma ratio approximately 0.5. Potential adverse effects in nursing infant including jaundice and breast enlargement. Use during lactation not recommended unless clearly necessary. May reduce milk production and quality.
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 approved; contraindicated in pregnancy. Pharmacokinetic changes in pregnancy (increased clearance, volume of distribution) could reduce efficacy if used, but use is contraindicated.
Contraindicated in pregnancy; no dose adjustments applicable. Discontinue medication immediately upon pregnancy detection.
SPRINTEC (ethinyl estradiol/norgestimate) is a combined oral contraceptive. Prescribe with caution in women with migraine with aura due to increased stroke risk. If a dose is missed, take as soon as remembered; if >24 hours late, use backup contraception for 7 days. Monitor blood pressure at initiation and annually. Discontinue if pregnancy is suspected or confirmed. Advise that antibiotics (e.g., rifampin) and anticonvulsants (e.g., phenytoin) may reduce efficacy.
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 each day, in the order directed on the pill pack.,If you miss a pill, refer to the package insert or consult your healthcare provider; use backup contraception as directed.,This medication does not protect against HIV or other sexually transmitted infections.,Common side effects include nausea, breast tenderness, and breakthrough bleeding; these often improve within a few cycles.,Seek immediate medical attention for symptoms of blood clots: sudden leg pain/swelling, chest pain, shortness of breath, or sudden severe headache.,Inform your provider about all medications, including over-the-counter drugs and herbal supplements, especially St. John's Wort.
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 SPRINTEC vs ALYACEN 1/35, answered by our medical review team.
SPRINTEC is a Oral Contraceptive that works by Combination of ethinyl estradiol and norgestimate suppresses gonadotropin release, inhibiting ovulation and altering cervical mucus and endometrium to prevent pregnancy.. 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 SPRINTEC 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 SPRINTEC is: One tablet (0.25 mg norgestimate, 0.035 mg ethinyl estradiol) orally once daily at the same time each day for 21 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 SPRINTEC 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. SPRINTEC is classified as Category C. FDA Pregnancy Category X. Use contraindicated in pregnancy. First trimester: Major congenital anomalies including cardiovascular and limb defects; increased risk of neural tube def. 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.