LO MINASTRIN FE
Clinical safety rating
cautionComprehensive clinical and safety monograph for LO MINASTRIN FE (LO MINASTRIN FE).
Combination oral contraceptive containing ethinyl estradiol (estrogen) and norethindrone (progestin). Inhibits ovulation by suppressing gonadotropin release; increases viscosity of cervical mucus, inhibiting sperm penetration; alters endometrial lining, reducing implantation likelihood.
| Metabolism | Hepatic via CYP3A4 (ethinyl estradiol) and primarily reduction and conjugation (norethindrone); undergoes first-pass metabolism. |
| Excretion | Renal: 40-50% as conjugated metabolites; fecal: 20-30% via biliary excretion; unchanged drug <1%. |
| Half-life | Norethindrone: 8-11 hours; ethinyl estradiol: 12-16 hours. Steady-state achieved after 5-7 days of dosing. |
| Protein binding | Norethindrone: 97% bound (primarily to albumin and SHBG); ethinyl estradiol: 98% bound (primarily to albumin). |
| Volume of Distribution | Norethindrone: 4 L/kg; ethinyl estradiol: 2-4 L/kg; reflects extensive tissue distribution and binding to sex hormone receptors. |
| Bioavailability | Oral: norethindrone ~64%, ethinyl estradiol ~40-48% due to first-pass metabolism. |
| Onset of Action | Oral: contraceptive effect begins after 7 days of continuous dosing; requires 7 days of backup contraception if started after day 5 of menses. |
| Duration of Action | Oral: 24 hours; requires daily dosing to maintain contraceptive efficacy. Withdrawal bleed occurs during the 7-day placebo/iron period. |
| Molecular Weight | 340.46 |
1 tablet (1 mg norethindrone acetate/20 mcg ethinyl estradiol/ferrous fumarate 75 mg) orally once daily for 28 consecutive days.
| Dosage form | TABLET, CHEWABLE, TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (GFR ≥30 mL/min). Contraindicated in severe renal impairment (GFR <30 mL/min) or acute renal failure due to potential for hyperkalemia from ferrous fumarate. |
| Liver impairment | Contraindicated in Child-Pugh class B or C (moderate to severe hepatic impairment). For Child-Pugh class A, use caution; consider lower dose estrogen combination if necessary. |
| Pediatric use | Not indicated for use prepubertal. Approved for females of reproductive potential; safety and efficacy in children <12 years not established. Follow adult dosing postmenarche. |
| Geriatric use | Not indicated for use in postmenopausal women. In women >35 years who smoke, use is contraindicated due to increased cardiovascular risk. |
| 1st trimester | Contraindicated in pregnancy. COCs are not indicated during pregnancy. If pregnancy occurs, discontinue immediately. |
| 2nd trimester | Contraindicated in pregnancy. Use of COCs during second trimester is associated with increased risk of fetal harm. |
| 3rd trimester | Contraindicated in pregnancy. Use of COCs during third trimester may cause adverse effects on fetus. |
Clinical note
Comprehensive clinical and safety monograph for LO MINASTRIN FE (LO MINASTRIN FE).
| Placental transfer | Estrogens and progestins cross the placenta. Norethindrone acetate and ethinyl estradiol have been detected in cord blood and amniotic fluid. |
| Breastfeeding | Small amounts of contraceptive steroids and/or metabolites have been identified in breast milk, and can reduce milk production and change breast milk composition. Use is generally not recommended; if used, use lowest effective dose and monitor infant growth and development. |
| Lactation Rating | L4 - Possibly Hazardous |
| Teratogenic Risk | Pregnancy category X. Contraindicated in pregnancy due to risk of fetal harm. First trimester use associated with cardiovascular defects, neural tube defects; second/third trimester use associated with fetal genital changes, hepatic adenoma. |
| Fetal Monitoring | Not applicable if contraindicated. If inadvertently exposed, monitor for fetal anomalies via ultrasound; beta-hCG for pregnancy confirmation before initiation. |
| Fertility Effects | Returns to normal upon discontinuation. No permanent effect on fertility. |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptive use. Risk increases with age (>35 years) and with heavy smoking (≥15 cigarettes/day). Women >35 years who smoke should not use combination oral contraceptives.
| Serious Effects |
Hypersensitivity to any componentThrombophlebitis or thromboembolic disordersCerebrovascular or coronary artery diseaseKnown or suspected breast carcinomaUndiagnosed abnormal genital bleedingBenign or malignant liver tumor (active or history)Known or suspected pregnancyJaundice or hepatic impairmentHeavy smoking (≥15 cigarettes/day) and age ≥35 yearsUncontrolled hypertensionDiabetes with vascular involvementMigraine with auraMajor surgery with prolonged immobilization
| Precautions | Thrombotic disorders (thrombophlebitis, pulmonary embolism, cerebrovascular accidents, myocardial infarction), Hepatic disease (benign/malignant tumors), Hypertension, Gallbladder disease, Carbohydrate/lipid metabolism effects, Ocular changes (retinal thrombosis), Headache/migraine, Uterine bleeding irregularities, Depression, Cervical cancer screening, Pregnancy test prior to initiation, Lactation (possible decreased milk production) |
| Food/Dietary | No significant food interactions. Grapefruit juice may increase ethinyl estradiol levels, but clinical significance is minimal. Avoid alcohol if liver function is compromised. Iron absorption from ferrous fumarate is enhanced by vitamin C, but not clinically important. |
| Clinical Pearls | LO MINASTRIN FE is a low-dose combination oral contraceptive (1 mg norethindrone acetate / 20 mcg ethinyl estradiol) with ferrous fumarate tablets. It is indicated for contraception and may improve menstrual regularity. The iron component is not bioavailable during active hormone intake; iron tablets are placebo-day supplements. Monitor for thromboembolic risks, especially in smokers over 35. Breakthrough bleeding is common in the first few cycles. Do not use in hepatic disease or known pregnancy. |
| Patient Advice | Take one tablet daily at the same time; the last 7 tablets contain iron instead of hormones. · Missed dose: if missed within 12 hours, take it as soon as remembered; if more than 12 hours, skip the missed dose and continue schedule; use back-up contraception for 7 days. · Smoking increases risk of serious cardiovascular side effects; avoid smoking, especially if over 35 years old. · Inform your healthcare provider of any new onset headaches, chest pain, leg pain/swelling, or visual disturbances. · Breakthrough bleeding is common initially; if persistent, consult your doctor. · Use additional non-hormonal contraception during first 7 days of starting the pill. · Store at room temperature; keep out of reach of children; iron tablets may be harmful to children if ingested. |
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