ORTHO-NOVUM 1/50 21
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ORTHO-NOVUM 1/50 21 (ORTHO-NOVUM 1/50 21).
Combination oral contraceptive consisting of mestranol (estrogen) and norethindrone (progestin). Mestranol is converted to ethinyl estradiol, which suppresses gonadotropin release (FSH, LH) from the pituitary, inhibiting ovulation. Norethindrone induces changes in cervical mucus (increasing viscosity) and endometrial lining, creating a hostile environment for sperm implantation.
| Metabolism | Mestranol is rapidly demethylated to ethinyl estradiol, primarily by CYP2C9 and CYP3A4. Ethinyl estradiol and norethindrone undergo hepatic metabolism via CYP3A4, with conjugation and excretion in urine and feces. |
| Excretion | Renal 50-60% as glucuronide and sulfate conjugates of norethindrone and mestranol/metabolites; fecal 20-30% via biliary elimination. |
| Half-life | Norethindrone: biphasic terminal half-life 7-9 hours for parent compound, 8-11 hours for metabolites; clinical steady-state achieved after 5-7 days. |
| Protein binding | Norethindrone: 97-98% bound to albumin and sex hormone-binding globulin (SHBG); mestranol: 95-97% bound to albumin. |
| Volume of Distribution | Norethindrone: Vd 3-4 L/kg (approx. 210-280 L for 70 kg adult), indicating extensive tissue distribution; mestranol: Vd 1.5-2 L/kg. |
| Bioavailability | Norethindrone: oral bioavailability 40-60% due to first-pass metabolism; mestranol rapidly converted to ethinyl estradiol with oral bioavailability 40-50%. |
| Onset of Action | Oral: inhibition of ovulation occurs after 7-14 days of continuous daily dosing; peak serum concentrations reached 1-2 hours post-dose. |
| Duration of Action | Therapeutic effect (contraceptive protection) persists for 24 hours after each dose; requires daily administration; withdrawal bleeding occurs 2-3 days after last active pill. |
One tablet orally once daily for 21 days, followed by 7 tablet-free days. Each tablet contains 1 mg norethindrone and 50 mcg mestranol.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. Insufficient data for severe renal impairment (GFR < 30 mL/min); use with caution. |
| Liver impairment | Contraindicated in Child-Pugh class B or C (moderate to severe hepatic impairment). For Child-Pugh class A, use with caution and monitor liver function. |
| Pediatric use | Not indicated for use before menarche. Post-menarche: same as adult dosing (one tablet daily for 21 days) after evaluating individual risk factors. |
| Geriatric use | Not indicated for use in postmenopausal women due to increased risk of thrombotic events and lack of benefit. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ORTHO-NOVUM 1/50 21 (ORTHO-NOVUM 1/50 21).
| Breastfeeding | Excreted in breast milk in small amounts; M/P ratio not established. May reduce milk production and quality, especially with high-dose estrogens. Use during lactation is generally not recommended, particularly in early postpartum. Consider non-hormonal contraception. |
| Teratogenic Risk | First trimester: Mestranol and norethindrone are associated with a slightly increased risk of congenital anomalies, particularly cardiovascular defects and limb reduction defects, although absolute risk is low. Second and third trimesters: Continued exposure may lead to fetal adrenal suppression, liver impairment, and pseudointersexuality in female fetuses due to androgenic effects of norethindrone. Overall, contraceptive use during pregnancy is contraindicated. |
■ FDA Black Box Warning
Cigarette smoking increases the risk of serious cardiovascular events from combination oral contraceptive use. This risk increases with age, especially in women over 35, and with the number of cigarettes smoked. Women who use combination hormonal contraceptives should be strongly advised not to smoke.
| Serious Effects |
["Known or suspected pregnancy.","Current or history of thrombophlebitis or thromboembolic disorders.","History of DVT or PE.","Cerebrovascular or coronary artery disease.","Known or suspected breast carcinoma or estrogen-dependent neoplasia.","Undiagnosed abnormal genital bleeding.","Cholestatic jaundice of pregnancy or jaundice with prior OC use.","Hepatic adenoma or carcinoma.","Known hypersensitivity to any component."]
| Precautions | ["Increased risk of thromboembolic disorders (e.g., DVT, PE) and cardiovascular events (MI, stroke).","Elevated blood pressure.","Increased risk of gallbladder disease.","Hepatic adenoma or hepatocellular carcinoma.","Glucose intolerance and adverse effects on lipid metabolism.","Chloasma (melasma) exacerbated by UV exposure.","Retinal thrombosis or other ocular effects.","Menstrual irregularities and amenorrhea.","Cervical cancer risk (HPV-related)."] |
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| Fetal Monitoring | Monitor for pregnancy symptoms if accidental use during pregnancy; if continued exposure occurs, fetal ultrasound for anomalies, assess fetal growth, and monitor neonatal adrenal function and electrolyte balance postpartum. |
| Fertility Effects | Normal ovulation and fertility return after discontinuation; no permanent negative effects on fertility. Post-pill amenorrhea may occur but typically resolves within months. |