LOW-OGESTREL-21
Clinical safety rating
cautionComprehensive clinical and safety monograph for LOW-OGESTREL-21 (LOW-OGESTREL-21).
Combination oral contraceptive. Suppresses gonadotropin release (FSH and LH) via estrogen (ethinyl estradiol) and progestin (norgestrel), inhibiting ovulation. Also increases cervical mucus viscosity and alters endometrium.
| Metabolism | Hepatic via CYP3A4 isoenzymes (ethinyl estradiol and norgestrel undergo hydroxylation and conjugation). Enterohepatic circulation. |
| Excretion | Ethinyl estradiol and norgestrel are excreted primarily as glucuronide and sulfate conjugates in urine (50-60%) and feces (30-40%). |
| Half-life | Norgestrel: 18-28 hours; ethinyl estradiol: 13-27 hours. Steady-state achieved after 5-7 days. |
| Protein binding | Norgestrel: 93-95% (albumin, SHBG); ethinyl estradiol: 97-98% (albumin). |
| Volume of Distribution | Norgestrel: 3.5-4.5 L/kg; ethinyl estradiol: 2.5-3.5 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Oral: norgestrel >90%; ethinyl estradiol 40-50% (first-pass metabolism). |
| Onset of Action | Oral: 3-5 hours (peak plasma levels); contraceptive effect requires 7 days of continuous dosing for full suppression of ovulation. |
| Duration of Action | 24 hours (maintains suppression of ovulation with daily dosing); missed pills reduce efficacy. |
| Molecular Weight | 310.6 |
One tablet (norgestrel 0.3 mg/ethinyl estradiol 30 mcg) orally once daily for 21 days, followed by 7 pill-free days.
| Dosage form | TABLET |
| Renal impairment | No dosage adjustment required for mild to moderate renal impairment. Use is contraindicated in severe renal impairment or acute renal failure due to potential fluid retention. |
| Liver impairment | Contraindicated in acute or chronic hepatic dysfunction, including Child-Pugh class A, B, or C. Do not use. |
| Pediatric use | Not indicated for use before menarche. For postmenarchal adolescents, use same dosing as adults: one tablet daily for 21 days, then 7 days off. |
| Geriatric use | Not indicated for postmenopausal women. No specific geriatric dosing; contraindicated in women over 35 who smoke, and generally avoided in older women due to increased cardiovascular risk. |
| 1st trimester | Contraindicated. Risk of oral contraceptive use during first trimester includes potential for fetal anomalies; however, available data do not suggest a significant increase in birth defects. Use only if clearly needed and no alternative exists. |
| 2nd trimester | Contraindicated. Estrogen-containing contraceptives may increase risk of fetal harm, including possible teratogenicity and adverse effects on fetal development. Avoid use during second trimester. |
| 3rd trimester | Contraindicated. Exposure in third trimester has been associated with potential for urogenital abnormalities in the fetus, as well as maternal risks like thromboembolism. Avoid use. |
Clinical note
Comprehensive clinical and safety monograph for LOW-OGESTREL-21 (LOW-OGESTREL-21).
| Placental transfer | Yes, ethinyl estradiol and norgestrel cross the placenta. Cord blood concentrations are approximately 1-20% of maternal serum levels. |
| Breastfeeding | Excreted in breast milk in small amounts; may reduce milk production and composition. Use during breastfeeding is generally not recommended, especially in early postpartum period. Alternative contraception methods are preferred. |
| Lactation Rating | L4 - Possibly Hazardous |
| Teratogenic Risk | Pregnancy category X. Contraindicated in pregnancy. Fetal risk includes cardiovascular anomalies, neural tube defects, and limb reduction defects if exposed during first trimester. Second and third trimester exposure may cause masculinization of female fetuses due to progestin component. |
| Fetal Monitoring | Pregnancy test before initiation. Monitor for signs of thromboembolism, hypertension, hepatic dysfunction, and glucose intolerance. No specific fetal monitoring indicated if pregnancy excluded. |
| Fertility Effects | Temporary suppression of ovulation. Rapid return to baseline fertility upon discontinuation. No permanent impairment of reproductive function. |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events (e.g., myocardial infarction, thromboembolism, stroke). Risk increases with age (>35 years) and smoking severity. Women over 35 who smoke should not use this drug.
| Serious Effects |
Known or suspected pregnancyBreast cancer (current or history)Liver disease or tumorsUndiagnosed abnormal uterine bleedingThromboembolic disorders (e.g., DVT, PE)Cerebrovascular or coronary artery diseaseMigraine with aura (if age ≥35)Major surgery with prolonged immobilizationHeavy smoking (≥15 cigarettes/day) and age ≥35Uncontrolled hypertensionDiabetes with vascular diseaseValvular heart disease with complicationsInherited or acquired hypercoagulopathies
| Precautions | Thromboembolic disorders (venous and arterial), Cerebrovascular disease, Myocardial infarction, Hypertension, Hepatic adenoma or carcinoma, Gallbladder disease, Carbohydrate/lipid metabolism effects, Ocular changes (e.g., retinal thrombosis), Headache/migraine exacerbation, Uterine bleeding irregularities, Fetal development (discontinue if pregnancy suspected), Depression, Contact lens intolerance, Fluid retention, Breast cancer risk (ongoing surveillance), Hereditary angioedema |
| Food/Dietary | No significant food interactions. Grapefruit juice may slightly increase estrogen exposure but does not require avoidance. Alcohol does not impair contraceptive efficacy but may increase risk of nausea or missed doses. |
| Clinical Pearls | LOW-OGESTREL-21 is a low-dose estrogen-progestin combination oral contraceptive. Its effectiveness may be reduced by concomitant enzyme-inducing drugs (e.g., rifampin, carbamazepine, phenytoin, St. John's wort). Breakthrough bleeding and spotting are more common with low-dose formulations. Contraception is not reliable if two or more active pills are missed; backup contraception is required. Initiation on the first day of menstrual bleeding eliminates need for backup contraception. Advise patients to take pill at same time daily to maintain consistent hormone levels. |
| Patient Advice | Take one pill daily at the same time, even if you have spotting or bleeding between periods. · If you miss one pill, take it as soon as you remember and continue the next pill at the usual time; no backup is needed. · If you miss two consecutive active pills, take two pills daily for two days, then resume one daily; use backup contraception for 7 days. · Possible side effects include nausea, headache, breast tenderness, and irregular bleeding; these often improve after 3 cycles. · Smoking while using this pill increases risk of serious cardiovascular events; do not smoke if over 35 years old. · Use a backup method (e.g., condoms) until you have taken 7 consecutive active pills if starting for the first time after day 5 of menstrual cycle. · Store pills at room temperature away from moisture. |
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