LYBREL
Clinical safety rating
cautionComprehensive clinical and safety monograph for LYBREL (LYBREL).
Combination of levonorgestrel and ethinyl estradiol: suppression of gonadotropins (FSH and LH) via negative feedback, inhibiting ovulation; thickening of cervical mucus to impede sperm penetration; alteration of endometrium to reduce implantation likelihood.
| Metabolism | Levonorgestrel: primarily metabolized via reduction, hydroxylation, and conjugation; CYP3A4 involvement. Ethinyl estradiol: metabolized by CYP3A4 and undergoes glucuronidation and sulfation. |
| Excretion | Renal: 50-60% as metabolites, ~20% as parent drug; fecal: 30-40%; biliary: 10-20%. |
| Half-life | Terminal elimination half-life: 27 ± 8 hours; requires ~5 days to reach steady-state; clinical significance: missed doses lead to rapid loss of contraceptive efficacy. |
| Protein binding | 99% bound to albumin and sex hormone-binding globulin (SHBG). |
| Volume of Distribution | Vd: 1.7 ± 0.3 L/kg; indicates extensive tissue distribution (e.g., reproductive organs, liver). |
| Bioavailability | Oral: 88% (range 80-95%); first-pass metabolism reduces systemic exposure by ~12%. |
| Onset of Action | Oral: 7 days for full contraceptive effect; initial follicular suppression begins within 24 hours. |
| Duration of Action | Contraceptive effect persists for 28 days with daily dosing; after discontinuation, ovulation may resume within 2-3 weeks. |
| Molecular Weight | 310.5 |
One tablet (levonorgestrel 0.1 mg/ethinyl estradiol 0.02 mg) orally once daily for 21 days, followed by 7 placebo tablets for 28-day cycle.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. Not studied in severe renal impairment (GFR <30 mL/min); use not recommended. |
| Liver impairment | Contraindicated in Child-Pugh class B and C hepatic impairment. Use with caution in Child-Pugh class A; monitor liver function. |
| Pediatric use | Safety and efficacy not established in postmenarchal pediatric patients for oral contraception. Use same dosing as adults for appropriate indications. |
| Geriatric use | Not indicated for use in postmenopausal women; no age-specific data. |
| 1st trimester | Contraindicated in first trimester due to increased risk of fetal cardiovascular and neural tube defects. Use only if benefit outweighs risk. |
| 2nd trimester | Contraindicated in second trimester due to risk of fetal adverse effects. Avoid use unless absolutely necessary. |
| 3rd trimester | Contraindicated in third trimester due to possible androgenic effects and fluid retention. Avoid use. |
Clinical note
Comprehensive clinical and safety monograph for LYBREL (LYBREL).
| Placental transfer | Crosses placenta; sufficient evidence of transfer. |
| Breastfeeding | Enters breast milk; may interfere with lactation and cause adverse effects in infant. Avoid breastfeeding during therapy and for 1 month after last dose. |
| Lactation Rating | L5 (Contraindicated) or 'Avoid' |
| Teratogenic Risk | Combined hormonal contraceptives (CHCs) like Lybrel (levonorgestrel/ethinyl estradiol) are contraindicated in pregnancy due to potential fetal harm. First trimester exposure is associated with a slightly increased risk of congenital anomalies, particularly cardiovascular and limb defects, though absolute risk is low. Second and third trimester exposure may lead to adverse outcomes including fetal growth restriction, preterm birth, and neonatal withdrawal symptoms. Data from observational studies suggest no major teratogenic risk at typical contraceptive doses, but use is not recommended once pregnancy is confirmed. |
| Fetal Monitoring | If unintentional use in pregnancy occurs, monitor fetal growth and anatomy via ultrasound. In late pregnancy exposure, monitor neonate for signs of hormonal withdrawal (e.g., irritability, feeding difficulties). No specific maternal monitoring required beyond routine prenatal care, but assess for thrombotic events (e.g., deep vein thrombosis, pulmonary embolism) if used inadvertently during pregnancy. |
| Fertility Effects | Lybrel suppresses ovulation, providing contraception. After discontinuation, fertility returns promptly (usually within 1-3 months). No evidence of permanent impairment of fertility. Ovarian function returns to baseline after cessation of use. |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptive use. Risk increases with age (especially in women >35 years) and with number of cigarettes smoked. Women who use oral contraceptives should be strongly advised not to smoke.
| Serious Effects |
PregnancyHistory of or current thromboembolic disordersCerebrovascular diseaseCoronary artery diseaseKnown or suspected carcinoma of the breastUndiagnosed abnormal genital bleedingCholestatic jaundice of pregnancy or jaundice with prior oral contraceptive useHepatic adenoma or carcinomaKnown hypersensitivity to components
| Precautions | Thrombotic disorders and cardiovascular events (especially in smokers >35 years), Elevated blood pressure, Gallbladder disease, Hepatic neoplasia, Glucose intolerance, Hereditary angioedema, Chloasma, Ocular changes (e.g., retinal thrombosis) requiring discontinuation |
| Food/Dietary | No specific foods are known to interact with Lybrel. Grapefruit juice may slightly increase ethinyl estradiol levels but effect is not clinically significant. Avoid St. John's wort as it may reduce contraceptive efficacy. |
| Clinical Pearls | Lybrel is a continuous combined oral contraceptive (COC) containing levonorgestrel 90 mcg and ethinyl estradiol 20 mcg, designed to eliminate monthly withdrawal bleeding. It is taken daily without placebo pills. Breakthrough bleeding and spotting are common in the first 6–12 months. Patients should be counseled that amenorrhea may take up to a year to achieve. Lybrel does not protect against STIs. It is contraindicated in smokers over 35, hypertension (≥160/100 mmHg), migraine with aura, and thromboembolic disorders. Drug interactions with CYP3A4 inducers (e.g., rifampin, carbamazepine, St. John's wort) may reduce efficacy. |
| Patient Advice | Take one pill every day at the same time, with or without food. There are no placebo pills, so you will take an active pill daily. · You may experience irregular bleeding or spotting, especially during the first 6–12 months. This is normal and usually decreases over time. · Do not expect a regular menstrual period. Most women will have no bleeding after one year of use. · If you miss pills, follow the package instructions. Missing pills increases the risk of pregnancy and may cause bleeding. · Use a backup method of contraception (like condoms) if you miss two or more pills or start a new pack late. · This medication does not protect against HIV or other sexually transmitted infections. · Tell your healthcare provider if you have new or severe headaches, chest pain, leg pain, vision changes, or jaundice. · Do not smoke while taking this medication, as smoking increases the risk of serious cardiovascular side effects. · Inform all healthcare providers that you are taking Lybrel, especially before surgery or blood tests. · Store at room temperature away from moisture and heat. |
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