NORINYL 1+80 21-DAY
Clinical safety rating
cautionComprehensive clinical and safety monograph for NORINYL 1+80 21-DAY (NORINYL 1+80 21-DAY).
Combination oral contraceptive containing norethindrone (a progestin) and ethinyl estradiol (an estrogen). Inhibits ovulation by suppressing gonadotropin release (FSH and LH). Also increases cervical mucus viscosity and alters endometrial morphology.
| Metabolism | Ethinyl estradiol undergoes first-pass metabolism in the intestinal wall and liver via CYP3A4, with conjugation and enterohepatic recirculation. Norethindrone is metabolized in the liver primarily via reduction and conjugation, with CYP3A4 involvement. Both are excreted in urine and feces. |
| Excretion | Renal (40-60% as metabolites), fecal (20-30%) |
| Half-life | Norethindrone: 8-11 hours; Mestranol: 12-24 hours (metabolized to ethinyl estradiol with half-life 20-27 hours). Steady-state after 5-7 days. |
| Protein binding | Norethindrone: 61% bound to albumin and SHBG; Mestranol/ethinyl estradiol: 98% bound to albumin |
| Volume of Distribution | Norethindrone: 3.6 L/kg; Mestranol/ethinyl estradiol: 1.5-4.0 L/kg |
| Bioavailability | Oral: norethindrone ~64%; mestranol ~40-60% (prodrug, converted to ethinyl estradiol) |
| Onset of Action | Oral: 7 days for contraceptive effect |
| Duration of Action | 24 hours; requires daily dosing; withdrawal bleed within 2-3 days after last active pill |
| Molecular Weight | 374.5 |
One tablet orally once daily for 21 days, followed by 7 days of no active treatment.
| Dosage form | TABLET |
| Renal impairment | No specific dose adjustment required for renal impairment. Use with caution in patients with renal dysfunction. |
| Liver impairment | Contraindicated in severe hepatic disease (Child-Pugh class C). For mild to moderate impairment (Child-Pugh A or B), use only if benefits outweigh risks and monitor liver function closely. |
| Pediatric use | Not indicated for use before menarche. For adolescents post-menarche, same adult dosing: one tablet orally once daily for 21 days, then 7-day pill-free interval. |
| Geriatric use | Not indicated for use after menopause. No specific dose adjustments in elderly women of reproductive age; standard adult dosing applies. |
| 1st trimester | Avoid in first trimester due to risk of fetal harm; not indicated for use during pregnancy. |
| 2nd trimester | Avoid in second trimester; may cause adverse effects on fetal development. |
| 3rd trimester | Avoid in third trimester; possible association with fetal abnormalities and pregnancy complications. |
Clinical note
Comprehensive clinical and safety monograph for NORINYL 1+80 21-DAY (NORINYL 1+80 21-DAY).
| Placental transfer | Yes, significant placental transfer; hormones cross placenta and can affect fetus. |
| Breastfeeding | Small amounts of contraceptive hormones can pass into breast milk; may reduce milk production and quality. Use with caution in nursing mothers, especially during early postpartum period. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | First trimester: No conclusive evidence of major malformations from combined hormonal contraceptives; however, data are limited. Second/third trimester: Use is contraindicated due to possible adverse effects on fetal development, including potential masculinization of female genitalia (androgenic progestin) and other hormonal effects, though the risk is low with norethindrone. Postnatal: No specific long-term effects documented. |
| Fetal Monitoring | No standard monitoring required during pregnancy since drug is contraindicated. If exposure occurs, routine obstetric care and fetal ultrasound for anatomy assessment are recommended. |
| Fertility Effects | Temporary; after discontinuation, return to fertility may be delayed by a few months but no permanent effect on fertility. |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events. Risk increases with age (especially >35 years) and heavy smoking (≥15 cigarettes/day). Women who use combination oral contraceptives should be strongly advised not to smoke.
| Serious Effects |
PregnancyThrombophlebitis or thromboembolic disordersHistory of deep vein thrombosis or pulmonary embolismCerebrovascular diseaseCoronary artery diseaseKnown or suspected breast cancerEstrogen-dependent neoplasiaUndiagnosed abnormal genital bleedingCholestatic jaundice of pregnancy or jaundice with prior pill useHepatic adenoma or carcinomaKnown or suspected pregnancy
| Precautions | Thrombotic events (venous thromboembolism, stroke, MI), Cigarette smoking, Hypertension, Gallbladder disease, Hepatic neoplasia, Carbohydrate/lipid effects, Headache/migraine, Bleeding irregularities, Use in pregnancy, Diabetes, Depression, Hereditary angioedema, Chloasma, Hepatic impairment, Renal impairment, Breast cancer risk |
| Food/Dietary | No significant food interactions. Grapefruit juice may slightly increase estrogen levels but effect is minimal. Maintain consistent intake to avoid gastrointestinal upset. |
| Clinical Pearls | NORINYL 1+80 21-DAY is a high-estrogen-dose combination oral contraceptive (1 mg norethindrone, 80 mcg mestranol). Use with caution in patients with cardiovascular risk factors; contraindicated in women over 35 who smoke. Mestranol is a prodrug that requires hepatic conversion to ethinyl estradiol; lower potency compared to ethinyl estradiol on a mcg basis. Monitor for thromboembolic events, especially in the first year of use. Consider alternative formulations if breakthrough bleeding occurs. |
| Patient Advice | Take one tablet daily at the same time each day for 21 days, then no tablets for 7 days. · If you miss a pill, follow the package instructions; use backup contraception as directed. · This medication does not protect against HIV or other sexually transmitted infections. · Seek immediate medical attention for sudden chest pain, shortness of breath, leg pain or swelling, severe headache, or vision changes. · Inform your healthcare provider if you smoke or have a history of blood clots, migraines, or hypertension. |
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