ZOVIA 1/50E-21
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZOVIA 1/50E-21 (ZOVIA 1/50E-21).
Combination estrogen-progestin contraceptive: Ethinyl estradiol suppresses gonadotropin release via negative feedback on hypothalamic-pituitary axis, inhibiting ovulation; Norethindrone induces cervical mucus thickening and endometrial thinning, impeding sperm penetration and implantation.
| Metabolism | Ethinyl estradiol: Primarily metabolized via CYP3A4 hydroxylation, with conjugation (glucuronidation and sulfation). Norethindrone: Undergoes reduction, hydroxylation, and conjugation; major metabolite is 5α-dihydronorethindrone. |
| Excretion | Renal: ~50% (metabolites); Fecal: ~30% (metabolites); Biliary: minor; Unchanged drug: <1% renal. |
| Half-life | Terminal elimination half-life: 13±3 hours (range 10-20 h) for the progestin component; clinical context: steady-state achieved within 5 days, with minimal accumulation. |
| Protein binding | Norethindrone: ~95% bound (albumin and SHBG); Ethinyl estradiol: ~97% bound (albumin). |
| Volume of Distribution | Norethindrone: 4 ± 1 L/kg; Ethinyl estradiol: 3.5 ± 1 L/kg; clinical meaning: extensive tissue distribution, not limited to plasma. |
| Bioavailability | Norethindrone: ~65% (oral); Ethinyl estradiol: ~65% (oral, with first-pass metabolism). |
| Onset of Action | Oral contraceptive effect: 7 days of continuous dosing required for full suppression of ovulation; individual effect may begin earlier (within 2-3 days) but complete contraceptive efficacy requires 7 days. |
| Duration of Action | Contraceptive effect: maintained during active pill taking; after last active pill, effect declines rapidly; ovulation may return within 2-4 weeks. |
| Molecular Weight | Ethinyl estradiol: 296.4 Da; Norethindrone: 298.4 Da |
| Action Class | Oral Contraceptive; Estrogen-Progestin Combination |
One tablet orally once daily for 21 consecutive days, followed by 7 placebo tablets for 28-day cycle.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for renal impairment; use with caution in severe renal disease due to potential fluid retention. |
| Liver impairment | Contraindicated in acute or chronic liver disease, including Child-Pugh class B and C; no established dose adjustment. |
| Pediatric use | Not indicated for use before menarche; post-menarche: same as adult dosing after onset of menstruation. |
| Geriatric use | Not indicated for use after menopause; no specific dose adjustment, but consider increased risk of thromboembolic events. |
| 1st trimester | Contraindicated: Risk of birth defects (neural tube defects, cardiovascular anomalies) and oral cleft. Pregnancy must be excluded before initiation. |
| 2nd trimester | Contraindicated: Can cause virilization of female fetus, hepatic adenoma risk, and other adverse effects. |
| 3rd trimester | Contraindicated: Risk of hepatic dysfunction, jaundice, and potential glucocorticoid effects on fetus. |
Clinical note
Comprehensive clinical and safety monograph for ZOVIA 1/50E-21 (ZOVIA 1/50E-21).
| Placental transfer | Both ethinyl estradiol and norethindrone cross the placenta; fetal drug levels reach approximately 30-50% of maternal serum levels. |
| Breastfeeding | Small amounts of ethinyl estradiol and norethindrone pass into breast milk; may reduce milk quantity and quality. Use only if benefit outweighs risk; monitor infant for jaundice and growth. Alternative contraception preferred. |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events from combined oral contraceptives (COCs). Risk increases with age (especially women >35 years) and number of cigarettes smoked. Women who use COCs should be strongly advised not to smoke.
| Common Effects | Nausea, Headache, Breast tenderness, Weight changes, Irregular menstrual bleeding, Mood changes, Acne |
| Serious Effects | Venous thromboembolism (deep vein thrombosis, pulmonary embolism), Arterial thromboembolism (myocardial infarction, stroke), Hepatic adenoma or hepatocellular carcinoma, Hypertension, Gallbladder disease, Thrombotic thrombocytopenic purpura (TTP), Hemolytic uremic syndrome (HUS) |
PregnancyHistory of or current thromboembolic disordersCerebrovascular or coronary artery diseaseKnown or suspected breast carcinomaUndiagnosed abnormal genital bleedingCholestatic jaundice of pregnancy or jaundice with prior pill useHepatic adenoma or carcinomaActive liver disease with abnormal liver function
| Precautions | Thrombotic disorders (venous thromboembolism, arterial thromboembolism, stroke, myocardial infarction) - discontinue if suspected, Cigarette smoking (especially >35 years) increases cardiovascular risk, Hypertension - monitor blood pressure; discontinue if hypertension develops, Gallbladder disease (cholecystitis, cholelithiasis), Hepatic neoplasia (benign and malignant), Carbohydrate and lipid effects (monitor in prediabetic/diabetic patients), Headache/migraine - evaluate if new or worsening, Uterine bleeding irregularities, Depression, Ocular abnormalities (retinal thrombosis) - discontinue if papilledema or visual disturbances, Effect on binding globulins (e.g., SHBG, CBG, TBG), Hereditary angioedema (exogenous estrogens may induce or exacerbate symptoms), Chloasma (may persist after discontinuation) |
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| Lactation Rating | L3 (Moderate Risk) |
| Teratogenic Risk | FDA Pregnancy Category X. Contraindicated in pregnancy due to risk of fetal harm. First trimester exposure associated with cardiovascular defects (0.1-1% risk) and limb reduction defects (0.01-0.1%). Second and third trimester exposure may increase risk of fetal genital tract abnormalities, hepatic adenoma, and possible carcinogenesis. Discontinue immediately if pregnancy occurs. |
| Fetal Monitoring | Monitor blood pressure at baseline and regularly; assess for thrombotic events (DVT, PE) and hepatic tumors. Perform pregnancy test before initiating and monthly thereafter. Inadvertent use during pregnancy requires fetal ultrasound for anatomical evaluation, particularly cardiac and limb structures. |
| Fertility Effects | Suppresses ovulation, thereby temporarily reducing fertility. Return to normal fertility typically occurs within 1-2 cycles after discontinuation. No permanent negative impact on fertility; may improve menstrual cycle regularity in some patients. |
| Food/Dietary | No specific dietary restrictions required. However, grapefruit juice may increase estrogen levels; avoid excessive consumption. Food does not significantly affect absorption. High-fat meals might delay absorption slightly but not clinically relevant. |
| Clinical Pearls | Zovia 1/50E-21 is a combination oral contraceptive containing ethynodiol diacetate 1 mg and ethinyl estradiol 50 mcg. The higher estrogen dose (50 mcg) increases thromboembolic risk; avoid in patients >35 who smoke, with migraines with aura, or history of VTE. Missed dose management: if one pill missed, take as soon as remembered; if two missed, take two pills for two days; if three missed, use backup contraception and consider emergency contraception. Drug interactions: rifampin, certain anticonvulsants (phenytoin, carbamazepine), St. John's Wort reduce efficacy. |
| Patient Advice | Take one pill daily at the same time each day to maintain effectiveness. · Begin the active pill pack on the first day of menstruation or the first Sunday after onset. · Use backup contraception (e.g., condoms) for the first 7 days if starting after day 5 of cycle. · If you miss a pill, refer to the missed dose instructions in the package insert. · Report any leg pain, chest pain, severe headache, or sudden visual changes immediately. · This medication does not protect against HIV or other sexually transmitted infections. · Grapefruit juice may increase estrogen levels; avoid large quantities. · Do not use during pregnancy; discontinue if pregnancy is confirmed. |