Comparative Pharmacology
Head-to-head clinical analysis: MICROGESTIN 1 5 30 versus MICROGESTIN 1 20.
Peer-Reviewed Evidence
Head-to-head clinical analysis: MICROGESTIN 1 5 30 versus MICROGESTIN 1 20.
MICROGESTIN 1.5/30 vs MICROGESTIN 1/20
Head-to-head clinical comparison of therapeutic indices and safety profiles.
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.
Combination oral contraceptive containing estrogen (ethinyl estradiol) and progestin (norethindrone acetate). Inhibits gonadotropin secretion (FSH, LH) via negative feedback, preventing ovulation. Also causes cervical mucus thickening and endometrial thinning.
Prevention of pregnancyAcne vulgaris (off-label, for women who desire contraception and have not responded to topical therapy)Dysmenorrhea (off-label)Endometriosis (off-label)Menorrhagia (off-label)Functional ovarian cysts (off-label)
Prevention of pregnancyTreatment of moderate acne vulgaris in females ≥15 years who have achieved menarche and are using oral contraception (FDA approved for this indication with 20 mcg ethinyl estradiol formulation)
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.
One tablet (norethindrone acetate 1 mg / ethinyl estradiol 20 mcg) orally once daily for 21 consecutive days, followed by 7 days of placebo or no tablets.
None Documented
None Documented
Norethindrone: 8-11 hours; Ethinyl estradiol: 13-19 hours. Steady-state reached within 5-7 days.
Norethindrone: 5.2-12.8 hours (mean ~8 hours); Ethinyl estradiol: 7-20 hours (mean ~13 hours); hepatic impairment prolongs.
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.
Ethinyl estradiol metabolized primarily by CYP3A4 via hydroxylation; also conjugated with sulfate and glucuronic acid. Norethindrone acetate deacetylated to norethindrone, then metabolized by reduction and conjugation; CYP3A4 minor role.
Renal: ~50-60% (primarily as glucuronide conjugates of ethinyl estradiol and norethindrone); Fecal: ~40-50% (via biliary elimination)
Renal: 40% as metabolites, 20% as glucuronide and sulfate conjugates; Fecal: 35%; Biliary: <5%.
Norethindrone: 90-95% bound to SHBG and albumin; Ethinyl estradiol: 95-98% bound to albumin, with 2-5% free.
Norethindrone: 60-80% bound to SHBG and albumin; Ethinyl estradiol: 95-98% bound to albumin.
Norethindrone: 3-5 L/kg; Ethinyl estradiol: 2-4 L/kg. High Vd indicates extensive tissue distribution.
Norethindrone: 3.4-5.5 L/kg; Ethinyl estradiol: 2.6-4.4 L/kg; reflects extensive tissue distribution.
Oral: Norethindrone ~64-75%; Ethinyl estradiol ~45-60% due to first-pass metabolism.
Oral: Norethindrone 64-70%; Ethinyl estradiol 38-48% (first-pass metabolism).
No dose adjustment is required for patients with renal impairment. However, because of potential fluid retention, use with caution in patients with renal dysfunction.
No specific dose adjustment recommended; data limited. Use caution in patients with significant renal impairment due to potential fluid retention.
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.
Contraindicated in severe hepatic disease (Child-Pugh C) due to impaired steroid metabolism. Use lowest effective dose in mild to moderate impairment (Child-Pugh A/B) with close monitoring.
Safety and effectiveness in pediatric patients under 18 years have not been established. Not indicated for use before menarche.
Not indicated for use before menarche. Post-menarche: same as adult dosing (one tablet daily) with monitoring for adverse effects.
Not indicated for use in postmenopausal women. No specific dosing recommendations in elderly; evaluate risk-benefit considering comorbidities (e.g., cardiovascular disease).
Not indicated for use after menopause due to increased risk of thromboembolic events and cardiovascular complications.
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.
Cigarette smoking increases risk of serious cardiovascular events (e.g., myocardial infarction, stroke, thromboembolism) from COC use. Risk increases with age (especially >35) and number of cigarettes smoked. Women >35 who smoke should not use COCs.
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.
["Risk of thromboembolic disorders (e.g., DVT, PE, stroke, MI) - discontinue if symptoms occur","Increased risk of myocardial infarction, especially in smokers ≥35","Elevated blood pressure - monitor periodic BP","Gallbladder disease risk","Hepatic neoplasia risk (benign/malignant) - discontinue if jaundice develops","May worsen diabetes, hyperlipidemia, or migraines","Women with history of depression should be monitored","Retinal thrombosis - discontinue if visual symptoms occur","Increased risk of pancreatitis in women with hypertriglyceridemia","Possible increase in breast cancer risk - individual risk/benefit assessment"]
Active or history of thrombophlebitis or thromboembolic disorders. Cerebrovascular or coronary artery disease. Known or suspected pregnancy. Undiagnosed abnormal uterine bleeding. Known or suspected breast carcinoma or other estrogen-/progestin-sensitive neoplasia. Hepatic adenoma or carcinoma. Jaundice or cholestatic jaundice of pregnancy, or history of jaundice with prior oral contraceptive use. Acute or chronic hepatocellular disease with abnormal liver function. Heavy smoking (≥15 cigarettes/day) in women >35 years. Hypersensitivity to any component.
["Thrombophlebitis or thromboembolic disorders (current or history)","Cerebrovascular or coronary artery disease (current or history)","Known or suspected breast carcinoma","Undiagnosed abnormal genital bleeding","Known or suspected pregnancy","Hepatic adenoma or carcinoma (current or history)","Jaundice or liver disease with impaired function (active)","Hypersensitivity to any component","Age >35 and smokes"]
Data Pending Review
Data Pending Review
No significant food interactions. Grapefruit juice may slightly increase estrogen levels but no specific restriction. Consistent dietary habits are recommended to avoid cycle irregularities.
No specific food restrictions; however, grapefruit juice may increase estrogen levels and is best avoided. High-fat meals may delay absorption but not clinically significant.
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.
Microgestin 1/20 (norethindrone acetate/ethinyl estradiol) is contraindicated in pregnancy. First trimester exposure has been associated with a small increase in risk of congenital anomalies, including cardiovascular and limb defects. Use in second and third trimesters may cause fetal harm, including female pseudohermaphroditism with high doses of progestins.
Small amounts of oral contraceptive steroids (including norethindrone and ethinyl estradiol) are excreted in breast milk. The M/P ratio is approximately 0.5 for norethindrone and 0.01–0.02 for ethinyl estradiol. Use during lactation may decrease milk production and quality. Not recommended for use in nursing mothers until weaning is complete. Alternative methods of contraception should be considered.
Small amounts of contraceptive steroids have been identified in breast milk, with an estimated M/P ratio of approximately 0.3 for ethinyl estradiol. Norethindrone acetate is also excreted. Use may reduce milk production and composition, especially with early postpartum use. Generally not recommended during breastfeeding due to potential effects on the infant.
No dosing adjustment is applicable as the drug is contraindicated in pregnancy. Pharmacokinetic changes in pregnancy (e.g., increased plasma volume, altered hepatic metabolism) are not relevant since use is contraindicated. Inadvertent exposure should prompt discontinuation and evaluation.
Microgestin 1/20 is contraindicated in pregnancy and should be discontinued immediately if pregnancy is suspected. No dose adjustments are applicable as the drug is not used during pregnancy. Physiological changes in pregnancy may affect pharmacokinetics, but no established dosing recommendations exist due to contraindication.
Category C
Category C
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.
Initiate on first day of menstrual period or first Sunday after onset; no need for back-up contraception if started within first 5 days. Missed pill protocols: if 1 pill missed, take as soon as remembered; if 2+ pills missed, take last missed pill, use back-up for 7 days. May reduce menstrual cramps and acne. Contraindicated in smokers over 35 and those with history of DVT or migraine with aura.
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).
Take one tablet daily at the same time to maintain steady hormone levels.If you miss a pill, refer to the package insert for instructions; use backup contraception if needed.Common side effects include nausea, breast tenderness, and breakthrough bleeding, which usually improve after 2-3 cycles.This medication does not protect against HIV or other STDs; use condoms for protection.Notify your provider if you experience severe abdominal pain, chest pain, shortness of breath, or vision changes.