Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
PIMTREA 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
PIMTREA is a small molecule inhibitor of the interaction between the PD-1 receptor and its ligands PD-L1 and PD-L2, acting as an immune checkpoint inhibitor to restore anti-tumor T-cell activity.
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.
Non-small cell lung cancer (NSCLC) with high PD-L1 expression (Trial 1),Advanced or metastatic NSCLC after prior chemotherapy (Trial 2)
Prevention of pregnancy
Intravenous 1000 mg/m2 over 10 minutes on days 1, 8, and 15 of a 28-day cycle.
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 of 2.5 to 4 hours; prolonged in renal impairment (up to 6–12 hours in severe impairment).
Norethindrone: 8-11 hours (terminal); ethinyl estradiol: 10-20 hours (terminal). The half-life supports once-daily dosing for oral contraceptive efficacy.
Primarily metabolized by CYP3A4 and CYP2D6; minor contributions from CYP2C9 and CYP2C19.
Ethinyl estradiol: primarily hepatic via CYP3A4; norethindrone: hepatic reduction and sulfate conjugation.
Primarily renal (approximately 70% as unchanged drug), with biliary/fecal excretion accounting for the remainder. Less than 5% 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%).
Approximately 20% bound to plasma proteins (albumin).
Norethindrone: 61% bound to albumin and SHBG; ethinyl estradiol: 97-98% bound to albumin.
0.3–0.4 L/kg; indicates distribution primarily into extracellular fluid.
Norethindrone: 3.8-4.5 L/kg; ethinyl estradiol: 2.0-4.0 L/kg. Large Vd indicates extensive tissue distribution.
Oral: 30–40% due to incomplete absorption and first-pass metabolism.
Oral: Norethindrone ~64%, ethinyl estradiol ~38-48% (due to first-pass metabolism).
For GFR 30-59 m L/min: reduce to 750 mg/m2; for GFR 15-29 m L/min: reduce to 500 mg/m2; for GFR <15 m L/min or dialysis: not recommended.
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.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 25-50%; Child-Pugh C: avoid use due to lack of data.
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 not established in pediatric patients; no recommended dosing.
Not indicated for use before menarche. For postmenarchal adolescents, same dosing as adults. Safety and efficacy established for contraception; weight-based dosing not applicable.
No specific dose adjustment based solely on age; monitor renal function and adjust accordingly.
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.
Immune-mediated adverse reactions, including pneumonitis, colitis, hepatitis, endocrinopathies, and nephritis, can be severe or fatal. Monitor for signs and symptoms. Withhold or permanently discontinue based on severity.
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.
Risk of immune-mediated pneumonitis, colitis, hepatitis, endocrinopathies, nephritis, and infusion-related reactions. Evaluate liver and renal function, thyroid function, and pregnancy status before initiation.
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
None known.
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. Grapefruit juice may slightly increase estrogen exposure but not clinically significant. Avoid St. John's Wort as it reduces efficacy.
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.
Pimtrea (ethinyl estradiol and drospirenone) is contraindicated in pregnancy. First trimester exposure: no increased risk of major birth defects from population-based cohort studies, but data are limited. Second and third trimester exposure: may increase risk of fetal harm, including cardiovascular and genitourinary anomalies, due to hormonal effects. Use only if clearly needed after weighing risks; discontinue if pregnancy occurs.
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 drospirenone are excreted in human milk in small amounts; estimated M/P ratio for drospirenone is approximately 0.37. Combination hormonal contraceptives may reduce milk production and quality. Not recommended during lactation, especially in the first 6 months postpartum. Use alternative contraception.
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.
Pimtrea is contraindicated during pregnancy; no dosing adjustments applicable. Pharmacokinetic changes during pregnancy (e.g., increased hepatic metabolism, volume of distribution) may reduce efficacy; however, use is not recommended. If inadvertently exposed, discontinue drug.
Contraindicated in pregnancy; no dose adjustments applicable. Discontinue medication immediately upon pregnancy detection.
Pimtrea (desogestrel/ethinyl estradiol) is a monophasic combined oral contraceptive. Counsel patients that missed pills increase pregnancy risk. Use with caution in smokers over 35 due to thromboembolism risk. Consider ARB/ACEI interaction for blood pressure control. No need for routine monitoring if asymptomatic.
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; if missed, refer to package insert for instructions.,Do not smoke while taking this pill, especially if over 35.,Report sudden severe headache, chest pain, leg pain, or vision changes.,May cause nausea, breast tenderness, or breakthrough bleeding initially.,Protection against pregnancy starts after 7 consecutive days of correct use.
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 PIMTREA vs ALYACEN 1/35, answered by our medical review team.
PIMTREA is a Oral Contraceptive that works by PIMTREA is a small molecule inhibitor of the interaction between the PD-1 receptor and its ligands PD-L1 and PD-L2, acting as an immune checkpoint inhibitor to restore anti-tumor T-cell activity.. 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 PIMTREA 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 PIMTREA is: Intravenous 1000 mg/m2 over 10 minutes on days 1, 8, and 15 of a 28-day cycle.. 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 PIMTREA 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. PIMTREA is classified as Category C. Pimtrea (ethinyl estradiol and drospirenone) is contraindicated in pregnancy. First trimester exposure: no increased risk of major birth defects from population-based cohort studie. 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.