N.E.E. 1/35 21
Clinical safety rating: caution
Comprehensive clinical and safety monograph for N.E.E. 1/35 21 (N.E.E. 1/35 21).
Combination estrogen-progestin contraceptive: ethinyl estradiol (estrogen) and norethindrone (progestin). Suppresses gonadotropin (FSH, LH) release via negative feedback, inhibiting ovulation; increases cervical mucus viscosity to impede sperm penetration; alters endometrial development to reduce implantation likelihood.
| Metabolism | Ethinyl estradiol: primarily hepatic via CYP3A4, undergoes conjugation (glucuronidation and sulfation). Norethindrone: hepatic reduction and conjugation, also metabolized by CYP3A4. Both undergo enterohepatic recirculation. |
| Excretion | Norethindrone (NET) and ethinyl estradiol (EE) are excreted primarily in urine (~50-60% as metabolites) and feces (~30-40% as metabolites); less than 1% excreted unchanged. |
| Half-life | Norethindrone: terminal half-life 7-8 hours; Ethinyl estradiol: terminal half-life 12-14 hours (with enterohepatic recycling). Clinically, steady state achieved after 5-7 days. |
| Protein binding | Norethindrone: ~97% bound (albumin, SHBG); Ethinyl estradiol: ~98% bound (albumin). |
| Volume of Distribution | Norethindrone: Vd 4-5 L/kg; Ethinyl estradiol: Vd 3-4 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Oral: Norethindrone ~64%; Ethinyl estradiol ~45% (first-pass metabolism). |
| Onset of Action | Oral: contraceptive effect requires 7 days of continuous dosing for full suppression of ovulation; immediate effect on cervical mucus within 24 hours. |
| Duration of Action | Contraceptive protection lasts for the 21-day dosing period; after last pill, ovulation returns typically within 1-2 weeks (range 7–21 days). |
One tablet orally once daily for 21 days, followed by 7 days off.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required. Use with caution in severe impairment. |
| Liver impairment | Contraindicated in Child-Pugh Class B or C (moderate to severe hepatic impairment). |
| Pediatric use | Not indicated in prepubertal children; use only after menarche per adult dosing. |
| Geriatric use | Not indicated for contraception postmenopausal; use lowest effective dose for hormone therapy if applicable. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for N.E.E. 1/35 21 (N.E.E. 1/35 21).
| Breastfeeding | Contraindicated in breastfeeding. Estrogen and progestins pass into breast milk; may reduce milk quantity and quality. Estrogen can suppress lactation. M/P ratio for norethindrone is approximately 0.5–1.0; for ethinyl estradiol, M/P ratio is about 0.2. Use postpartum only after breastfeeding is fully established and only if no alternative. Generally avoid. |
| Teratogenic Risk | N.E.E. 1/35 21 (norethindrone/ethinyl estradiol) is contraindicated in pregnancy. First trimester: No increased risk of major birth defects based on population data, but should not be used once pregnancy is confirmed. Second and third trimesters: Known risks include feminization of male fetus, cardiovascular and skeletal abnormalities, and potential for long-term effects on the child. Immediate discontinuation if pregnancy occurs. |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptive use. Risk increases with age (especially >35 years) and with heavy smoking (>15 cigarettes/day). Women over 35 who smoke should not use this product.
| Serious Effects |
["Thrombophlebitis, venous thromboembolism (current or history)","Cerebrovascular or coronary artery disease (current or history)","Known or suspected pregnancy","Undiagnosed abnormal genital bleeding","Known or suspected breast cancer (current or history)","Estrogen-dependent neoplasia (current or history)","Hepatic adenoma or carcinoma (current or history)","Active liver disease or impaired hepatic function (including jaundice with prior pill use)","Major surgery with prolonged immobilization","Hypersensitivity to any component of the product","Age >35 years and smoking"]
| Precautions | ["Increased risk of thromboembolic disorders (e.g., DVT, PE, stroke, MI)","Cigarette smoking significantly increases cardiovascular risk (see boxed warning)","Elevated blood pressure","Hepatic neoplasia (benign and malignant) reported with long-term use","Gallbladder disease","Carbohydrate and lipid metabolic effects (monitor in prediabetic/diabetic patients)","Headache (including migraine), discontinue if new or worsening pattern","Bleeding irregularities (breakthrough bleeding, amenorrhea)","Chloasma (may persist after discontinuation)","Retinal thrombosis (discontinue if unexplained vision loss)"] |
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| Fetal Monitoring | Monitor blood pressure, renal function, hepatic function, and glucose tolerance during pregnancy if inadvertent exposure. If used postpartum, monitor infant for jaundice and growth. No routine fetal monitoring recommended except standard prenatal care. In case of exposure, consider early ultrasound for fetal anatomy. |
| Fertility Effects | Reversible suppression of ovulation. Normal fertility typically returns within one cycle after discontinuation. No permanent negative impact on fertility. Use does not increase risk of infertility or future reproductive problems. |