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. |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ZOVIA 1/50E-21 (ZOVIA 1/50E-21).
| Breastfeeding | Excreted in breast milk in small amounts (estrogen: <1% of maternal dose; progestin: <1-3%). M/P ratio not well established for this specific combination. No adverse effects reported in nursing infants at typical doses; however, may reduce milk production and protein content. Consider alternative contraception in breastfeeding women, especially immediately postpartum. |
| 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. |
■ 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.
| Serious Effects |
["Thrombophlebitis or thromboembolic disorders (current or history)","Cerebrovascular or coronary artery disease (current or history)","Known or suspected breast carcinoma","Endometrial carcinoma or other estrogen-dependent neoplasia","Undiagnosed abnormal genital bleeding","Cholestatic jaundice of pregnancy or jaundice with prior oral contraceptive use","Hepatic adenoma or carcinoma","Known or suspected pregnancy","Hypersensitivity to any component","Active hepatitis or impaired 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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| 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. |