NORINYL 1+80 28-DAY
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NORINYL 1+80 28-DAY (NORINYL 1+80 28-DAY).
Combination oral contraceptive containing a progestin (norethindrone) and an estrogen (mestranol). Suppresses gonadotropin (FSH and LH) release via negative feedback, inhibiting ovulation. Also induces changes in cervical mucus and endometrium to impede sperm penetration and implantation.
| Metabolism | Norethindrone undergoes hepatic metabolism via reduction and conjugation; major enzyme CYP3A4. Mestranol is rapidly demethylated to ethinyl estradiol, which undergoes hepatic metabolism via CYP3A4 and conjugation. |
| Excretion | Norethindrone is primarily excreted in urine (approximately 60%) and feces (approximately 40%) as glucuronide and sulfate conjugates. Mestranol is metabolized to ethinyl estradiol; ethinyl estradiol and its metabolites are excreted in urine (40%) and feces (60%). |
| Half-life | Norethindrone: terminal elimination half-life of 5.3-10.5 hours; Mestranol (as ethinyl estradiol): terminal half-life of 7-20 hours. Clinically, steady state is achieved after 5-7 days of daily dosing; the half-life supports once-daily dosing for consistent hormonal levels. |
| Protein binding | Norethindrone: 80-85% bound to albumin and SHBG; Mestranol (as ethinyl estradiol): 95-98% bound to albumin. |
| Volume of Distribution | Norethindrone: Vd ~ 4.0 L/kg, indicating extensive tissue distribution; Mestranol (as ethinyl estradiol): Vd ~ 1.5-2.5 L/kg. |
| Bioavailability | Norethindrone: oral bioavailability ~ 64%; Mestranol: rapidly metabolized to ethinyl estradiol, with combined effects providing oral contraceptive efficacy. Both components are administered orally. |
| Onset of Action | Oral administration: contraceptive effect requires 7 days of continuous use to inhibit ovulation; for cycle control, effects begin within the first cycle. |
| Duration of Action | Contraceptive effect persists for at least 24 hours with daily dosing; after discontinuation, return of ovulation may occur within 1-2 weeks but can be delayed. |
One tablet (1 mg norethindrone / 80 mcg ethinyl estradiol) orally once daily for 28-day cycle without placebo.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required; use with caution in severe renal impairment (GFR <30 mL/min) due to potential fluid retention. |
| Liver impairment | Contraindicated in acute liver disease or decompensated cirrhosis (Child-Pugh class B or C). Use with caution in mild hepatic impairment (Child-Pugh class A) with monitoring. |
| Pediatric use | Not indicated for prepubertal females. Postmenarchal adolescents: same adult dosing; adjust if <45 kg with caution. |
| Geriatric use | Not indicated for postmenopausal women due to increased risk of thromboembolism and lack of contraceptive benefit. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for NORINYL 1+80 28-DAY (NORINYL 1+80 28-DAY).
| Breastfeeding | Mestranol and norethindrone are excreted into breast milk in small amounts. M/P ratio not reported. May reduce milk production and composition (decreased protein and fat content). Potential for adverse effects on the infant (e.g., jaundice, breast enlargement in males). Generally not recommended during breastfeeding; alternative contraception advised. |
| Teratogenic Risk | FDA Pregnancy Category X. Contraindicated in pregnancy due to estrogen component (mestranol) and progestin (norethindrone). First trimester: increased risk of congenital anomalies, including cardiovascular defects and limb reduction defects. Second and third trimesters: potential for androgenic effects on female fetus (pseudohermaphroditism), and possible long-term effects from estrogenic activity. Not recommended for use during pregnancy. |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptives. Risk increases with age (especially >35 years) and with heavy smoking (≥15 cigarettes/day). Women who use combination oral contraceptives should be strongly advised not to smoke.
| Serious Effects |
Thrombophlebitis, thromboembolic disorders, cerebral vascular disease, or past history of these conditions. Known or suspected pregnancy. Liver tumor (benign or malignant) or active liver disease. Known or suspected carcinoma of the breast or endometrium. Undiagnosed abnormal genital bleeding. Hypersensitivity to any component. Use of Hepatitis C drug combinations containing ombitasvir/paritaprevir/ritonavir, dasabuvir, or glecaprevir/pibrentasvir.
| Precautions | Increased risk of thrombotic and thromboembolic events (e.g., MI, stroke, VTE), especially in smokers >35 years and those with hypertension, diabetes, hyperlipidemia, or obesity. Discontinue if thrombotic event occurs. Hepatic neoplasia risk. Elevated blood pressure. Gallbladder disease. Carbohydrate/lipid effects. Worsening of depression. Fluid retention. Hereditary angioedema. Chloasma. Lens opacities. Discontinue if jaundice develops. Use caution with history of depression, diabetes, or familial hyperlipidemia. |
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| Fetal Monitoring | Monitor for pregnancy symptoms prior to initiating therapy. In case of accidental exposure during pregnancy, monitor fetal development via ultrasound. Assess for signs of pregnancy if therapy is ongoing. No specific monitoring required for fetal effects if used as directed (contraindicated in pregnancy). For lactation, observe infant for any adverse effects. |
| Fertility Effects | Oral contraceptives suppress ovulation and are used to prevent pregnancy. May cause temporary delay in return to fertility after discontinuation. In some cases, used to treat menstrual irregularities and endometriosis, which may improve fertility outcomes after cessation. No permanent impact on fertility. |