OVULEN-21
Clinical safety rating
cautionComprehensive clinical and safety monograph for OVULEN-21 (OVULEN-21).
Combination estrogen-progestin oral contraceptive; inhibits gonadotropin release, suppressing ovulation; increases viscosity of cervical mucus, impeding sperm penetration; alters endometrial development.
| Metabolism | Hepatic via CYP3A4; ethinyl estradiol undergoes oxidation and conjugation; ethynodiol diacetate is metabolized to norethindrone. |
| Excretion | Renal: 50-60% as metabolites; fecal: 30-40% as conjugates; biliary excretion significant. |
| Half-life | Ethinyl estradiol: 13-27 hours (mean ~17 hours); norethindrone: 5-14 hours (mean ~8 hours); terminal half-life supports once-daily dosing. |
| Protein binding | Ethinyl estradiol: 97-98% bound to albumin; norethindrone: 80-85% bound to albumin and SHBG. |
| Volume of Distribution | Ethinyl estradiol: 2.5-4 L/kg; norethindrone: 2.3-3.4 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Oral: ethinyl estradiol 38-48%; norethindrone 64-70% (first-pass metabolism reduces bioavailability). |
| Onset of Action | Oral: 24 hours for ovulation suppression; 7 days for full contraceptive effect when started on day 1 of cycle. |
| Duration of Action | 24 hours; requires daily dosing to maintain contraceptive efficacy. |
| Molecular Weight | Ethinyl estradiol: 296.4 Da; Ethynodiol diacetate: 380.5 Da |
One tablet (ethinyl estradiol 0.05 mg and norethindrone 1 mg) orally once daily for 21 consecutive days, followed by 7 days without medication.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for renal impairment; use with caution in patients with impaired renal function. |
| Liver impairment | Contraindicated in patients with hepatic impairment (Child-Pugh class B or C); use not recommended. |
| Pediatric use | Not indicated for use before menarche. |
| Geriatric use | Not indicated for use after menopause. |
| 1st trimester | Contraindicated due to risk of congenital defects, particularly cardiovascular and limb defects, associated with progestin and estrogen exposure. |
| 2nd trimester | Contraindicated due to potential adverse effects on fetal development, including masculinization of female fetuses. |
| 3rd trimester | Contraindicated due to risk of neonatal complications such as respiratory distress syndrome and jaundice. |
Clinical note
Comprehensive clinical and safety monograph for OVULEN-21 (OVULEN-21).
| Placental transfer | Extensive; ethinyl estradiol and ethynodiol diacetate cross the placenta and can affect fetal development. |
| Breastfeeding | Excreted in breast milk; may reduce milk production and quality. Use only if benefits outweigh risks; monitor infant for adverse effects. |
| Lactation Rating | L4 - Possibly Hazardous |
| Teratogenic Risk | First trimester: Increased risk of neural tube defects, congenital heart defects, and limb reduction defects. Second and third trimesters: Potential for feminization of male fetus, vaginal adenosis, and cervical ectropion. Also associated with increased risk of miscarriage and stillbirth. |
| Fetal Monitoring | Monitor for venous thromboembolism, hypertension, hepatic dysfunction, and glucose intolerance. Fetal ultrasound for congenital anomalies if exposed in first trimester. |
| Fertility Effects | Suppresses ovulation. Reversible upon discontinuation. No long-term impact on fertility. |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular side effects from combination oral contraceptives. Risk increases with age and heavy smoking (≥15 cigarettes/day). Women over 35 who smoke should not use this product.
| Serious Effects |
PregnancyThrombophlebitis or thromboembolic disordersCerebrovascular or coronary artery diseaseKnown or suspected breast cancerUndiagnosed abnormal genital bleedingLiver tumors or impaired liver functionHypersensitivity to any component
| Precautions | Increased risk of thromboembolic disorders; hypertension; gallbladder disease; hepatic neoplasia; glucose intolerance; blood pressure monitoring recommended; discontinue if jaundice or visual disturbances occur. |
| Food/Dietary | No significant food interactions. Grapefruit juice may increase estrogen levels; avoid excessive consumption. Maintain consistent dietary habits as high-fat meals may affect absorption. |
| Clinical Pearls | Ovulen-21 is a combination oral contraceptive containing ethynodiol diacetate and ethinyl estradiol. It carries an increased risk of thromboembolism, especially in smokers over 35. Prescribe with caution in patients with hypertension, migraine with aura, or history of DVT. Advise consistent timing to maintain efficacy. Consider alternative contraception in patients taking enzyme-inducing antiepileptics or rifampin. |
| Patient Advice | Take one pill daily at the same time for 21 days, then 7 days off. · Use backup contraception if you miss a dose or start late. · Report severe headaches, chest pain, leg swelling, or vision changes immediately. · Do not smoke while taking this medication, especially if over 35 years old. · May cause nausea, breast tenderness, or breakthrough bleeding, especially in first cycles. |
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