LO LARIN FE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LO LARIN FE (LO LARIN FE).
Combination of ethinyl estradiol (estrogen) and norethindrone (progestin) inhibits gonadotropin release, preventing ovulation; increases cervical mucus viscosity, impeding sperm penetration; alters endometrial lining, reducing implantation likelihood.
| Metabolism | Ethinyl estradiol: primarily metabolized via CYP3A4; norethindrone: reduced to active metabolite (ethynylestradiol) and also metabolized via CYP3A4. Both undergo conjugation (glucuronidation and sulfation). |
| Excretion | Renal: 30-50% as ethinyl estradiol metabolites and norethindrone metabolites; fecal: 30-50% primarily as norethindrone metabolites; biliary excretion contributes to enterohepatic circulation. |
| Half-life | Ethinyl estradiol: ~13-17 hours; norethindrone: ~8-12 hours; steady-state achieved within 5-7 days; clinical significance: missed doses may require backup contraception. |
| Protein binding | Ethinyl estradiol: ~97-98% bound to albumin and sex hormone-binding globulin (SHBG); norethindrone: ~90-95% bound to albumin and SHBG. |
| Volume of Distribution | Ethinyl estradiol: ~3-4 L/kg; norethindrone: ~4-5 L/kg; indicates extensive tissue distribution beyond plasma volume. |
| Bioavailability | Oral: ethinyl estradiol ~40-50% (first-pass metabolism); norethindrone ~60-70% (low first-pass effect). |
| Onset of Action | Oral: maximum contraceptive effect after 7 days of continuous dosing; immediate effect if started on day 1 of menstrual cycle. |
| Duration of Action | 24 hours per dose; contraceptive protection maintained with daily adherence; missed dose >24 hours increases pregnancy risk. |
One tablet orally once daily for 28 consecutive days. Each tablet contains norethindrone acetate 1 mg and ethinyl estradiol 20 mcg. Active tablets (21 days) followed by ferrous fumarate 75 mg inert tablets (7 days).
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. Contraindicated in acute renal disease or renal impairment with decreased renal function due to potential fluid retention and hyperkalemia. |
| Liver impairment | Contraindicated in acute hepatic disease, hepatic adenoma, or history of cholestatic jaundice. For mild Child-Pugh A: no data; use with caution. Moderate to severe (Child-Pugh B or C): contraindicated. |
| Pediatric use | Not indicated for use before menarche. Post-menarche adolescents: same dosing as adults (one tablet daily) with monitoring for thromboembolic risk. |
| Geriatric use | Not indicated for use in postmenopausal women. No specific geriatric dosing; avoid in women over 50 due to increased cardiovascular and thromboembolic risks. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for LO LARIN FE (LO LARIN FE).
| Breastfeeding | Enters breast milk. M/P ratio unknown. May reduce milk production and affect infant hormone levels. Use caution; consider risks vs benefits. |
| Teratogenic Risk | Pregnancy category X. Contraindicated in pregnancy. First trimester: Risk of cardiovascular defects, oral clefts, neural tube defects. Second and third trimesters: Risk of feminization of male fetus, hepatic adenoma, and possible reduced birth weight. |
| Fetal Monitoring |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptives. Risk increases with age and heavy smoking (≥15 cigarettes/day). Women over 35 who smoke should not use this product.
| Serious Effects |
["Thrombophlebitis or thromboembolic disorders (current or history)","Cerebrovascular or coronary artery disease (current or history)","Known or suspected breast carcinoma","Carcinoma of the endometrium or other estrogen-dependent neoplasia","Undiagnosed abnormal genital bleeding","Cholestatic jaundice of pregnancy or jaundice with prior pill use","Hepatic adenoma or carcinoma (current or history)","Known or suspected pregnancy","Hypersensitivity to any component","Heavy smoking (≥15 cigarettes/day) and age >35"]
| Precautions | ["Thromboembolic disorders (VTE, stroke, MI) - increased risk especially in smokers >35","Carcinogenesis: possible increased risk of breast and cervical cancer","Hepatic effects: cholestatic jaundice, liver tumors","Gallbladder disease","Elevated blood pressure","COC use does not protect against HIV or other STDs","Ocular changes: retinal thrombosis, contact lens intolerance","Depression","Reduced efficacy with enzyme-inducing drugs"] |
Loading safety data…
| Monitor blood pressure, liver function, glucose tolerance, and signs of thromboembolism. Ultrasound for fetal anomalies if inadvertent exposure. |
| Fertility Effects | May delay return to fertility after discontinuation due to ovulation suppression, but no permanent negative effects on fertility. |