MICROGESTIN 1.5/30
Clinical safety rating
cautionComprehensive clinical and safety monograph for MICROGESTIN 1.5/30 (MICROGESTIN 1.5/30).
Combination oral contraceptive containing norethindrone acetate (progestin) and ethinyl estradiol (estrogen). Suppresses gonadotropin secretion (FSH, LH) via negative feedback on hypothalamic-pituitary axis, preventing ovulation. Also increases cervical mucus viscosity and alters endometrial receptivity.
| Metabolism | Norethindrone acetate is deacetylated to norethindrone, primarily metabolized via cytochrome P450 3A4 (CYP3A4) to reduced metabolites, sulfates, and glucuronides. Ethinyl estradiol is metabolized primarily by CYP3A4, undergoes hydroxylation, and undergoes conjugation (glucuronidation and sulfation). Both undergo enterohepatic recirculation. |
| Excretion | Renal: ~50-60% (primarily as glucuronide conjugates of ethinyl estradiol and norethindrone); Fecal: ~40-50% (via biliary elimination) |
| Half-life | Norethindrone: 8-11 hours; Ethinyl estradiol: 13-19 hours. Steady-state reached within 5-7 days. |
| Protein binding | Norethindrone: 90-95% bound to SHBG and albumin; Ethinyl estradiol: 95-98% bound to albumin, with 2-5% free. |
| Volume of Distribution | Norethindrone: 3-5 L/kg; Ethinyl estradiol: 2-4 L/kg. High Vd indicates extensive tissue distribution. |
| Bioavailability | Oral: Norethindrone ~64-75%; Ethinyl estradiol ~45-60% due to first-pass metabolism. |
| Onset of Action | Oral: Contraceptive effect achieved within 7 days of consistent daily dosing; peak hormone levels at 1-4 hours post-dose. |
| Duration of Action | 24 hours (daily dosing required). Clinical effect persists for the entire dosing interval if taken consistently. |
| Molecular Weight | Norethindrone: 298.42 Da; Ethinyl Estradiol: 296.40 Da (average for combined drug) |
| Action Class | Oral Contraceptive; Estrogen/Progestin Combination |
One tablet (norethindrone acetate 1.5 mg/ethinyl estradiol 30 mcg) orally once daily at the same time each day for 21 consecutive days, followed by 7 days of placebo tablets.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment is required for patients with renal impairment. However, because of potential fluid retention, use with caution in patients with renal dysfunction. |
| Liver impairment | Contraindicated in patients with acute liver disease or hepatocellular carcinoma. For Child-Pugh class A: use with caution; class B or C: not recommended due to potential for impaired hormone metabolism. |
| Pediatric use | Safety and effectiveness in pediatric patients under 18 years have not been established. Not indicated for use before menarche. |
| Geriatric use | Not indicated for use in postmenopausal women. No specific dosing recommendations in elderly; evaluate risk-benefit considering comorbidities (e.g., cardiovascular disease). |
| 1st trimester | Contraindicated due to increased risk of congenital anomalies, particularly cardiovascular and limb defects. Use only if necessary after ruling out pregnancy. |
| 2nd trimester | Risk of fetal harm; associated with masculinization of female fetus due to androgenic progestin. Avoid use unless critical. |
| 3rd trimester | Potential for withdrawal bleeding and preterm labor; avoid use. Risk of fetal harm persists. |
Clinical note
Comprehensive clinical and safety monograph for MICROGESTIN 1.5/30 (MICROGESTIN 1.5/30).
| Placental transfer | Norethindrone and ethinyl estradiol cross the placenta; documented in human studies. |
| Breastfeeding | Excreted in breast milk; may cause adverse effects in nursing infants, including jaundice and breast enlargement. Use only if benefit outweighs risk and monitor infant. |
| Lactation Rating | L4 - Possibly Hazardous |
| Teratogenic Risk | First trimester: An increased risk of cardiovascular defects and oral clefts following first-trimester exposure to oral contraceptives has been suggested but not confirmed. Norethindrone and ethinyl estradiol are not recommended during pregnancy. If pregnancy occurs, the drug should be discontinued. Second and third trimesters: Exposure to estrogens and progestins may cause fetal harm, including urogenital abnormalities in female fetuses (e.g., hypospadias in males, clitoral enlargement, labial fusion in females). Use is contraindicated during known or suspected pregnancy. |
| Fetal Monitoring | Monitor blood pressure regularly, especially if there is a history of hypertension. Perform pelvic exams annually, including Pap smear. Monitor for signs of thromboembolic events, depression, and glucose intolerance. In case of pregnancy, ultrasound for fetal development and anomaly screening. |
| Fertility Effects | Suppresses ovulation via inhibition of gonadotropin release. After discontinuation, return to fertility may be delayed but is not permanently impaired. Some women may experience anovulatory cycles temporarily post-discontinuation. |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events (thrombophlebitis, venous thromboembolism, stroke, myocardial infarction) from combination oral contraceptive use. Risk increases with age and heavy smoking (≥15 cigarettes/day). Women over 35 who smoke should not use this product.
| Common Effects | Nausea, Headache, Breast tenderness, Weight changes, Irregular menstrual bleeding, Mood changes |
| Serious Effects | Venous thromboembolism (deep vein thrombosis, pulmonary embolism), Arterial thromboembolism (myocardial infarction, stroke), Hepatic adenoma or hepatocellular carcinoma, Hypertension, Gallbladder disease, Retinal thrombosis |
Current or history of venous thromboembolismActive liver disease or hepatic adenomaKnown or suspected pregnancyCurrent or history of breast cancerUndiagnosed abnormal genital bleedingHypersensitivity to any component
| Precautions | Increased risk of thromboembolic disorders (venous thromboembolism, arterial thrombosis), stroke, myocardial infarction, especially in smokers >35 years. Hepatic neoplasia (benign and malignant), hypertension, gallbladder disease, carbohydrate/lipid effects, headache/migraine exacerbation, visual disturbances (retinal thrombosis). Breakthrough bleeding/spotting. Hepatic enzyme induction (e.g., rifampin) may reduce contraceptive efficacy. |
| Food/Dietary | No significant food interactions. Grapefruit juice may slightly increase estrogen levels but no specific restriction. Consistent dietary habits are recommended to avoid cycle irregularities. |
| Clinical Pearls | MICROGESTIN 1.5/30 (norethindrone acetate 1.5 mg/ethinyl estradiol 30 mcg) is a monophasic combined oral contraceptive. Its progestin component has mild androgenic activity, which may benefit some women with acne. Bleeding irregularities are common in the first 3 cycles. Counsel patients that missing pills increases pregnancy risk; strict adherence is critical. Evaluate baseline blood pressure and consider stopping if migraine with aura develops. Liver enzyme inducers (e.g., rifampin, certain anticonvulsants) may reduce efficacy. |
| Patient Advice | Take one tablet daily at the same time to maintain steady hormone levels. · If you miss a pill, refer to the package insert: take the missed pill as soon as remembered and use backup contraception (e.g., condoms) for 7 days. · Common side effects include nausea, breast tenderness, and spotting; these often improve after 3 cycles. · Smoking increases risk of serious cardiovascular side effects, especially if over 35 years old and smoking 15+ cigarettes daily. · Seek emergency care for leg pain/swelling, sudden severe headache, chest pain, or vision changes (possible blood clot or stroke). |
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