LARIN FE 1.5/30
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LARIN FE 1.5/30 (LARIN FE 1.5/30).
Combination oral contraceptive containing ethinyl estradiol (estrogen) and norethindrone (progestin). Suppresses gonadotropin release (FSH, LH) via negative feedback on hypothalamic-pituitary axis, inhibiting ovulation. Increases cervical mucus viscosity, reducing sperm penetration; alters endometrial receptivity. Norethindrone also decreases ovarian estrogen production.
| Metabolism | Ethinyl estradiol: primarily CYP3A4 metabolism with first-pass hepatic and intestinal metabolism; undergoes conjugation (glucuronidation and sulfation). Norethindrone: extensively metabolized via reduction, glucuronidation, and sulfation; CYP3A4 also involved. |
| Excretion | Ethinyl estradiol and norethindrone are primarily excreted via renal (urine) and fecal routes. Approximately 40-50% of ethinyl estradiol is excreted renally as metabolites, with 20-30% in feces. Norethindrone metabolites are excreted ~50-70% renally and 20-30% fecally. Less than 5% is excreted unchanged. |
| Half-life | Ethinyl estradiol terminal half-life is approximately 13-17 hours; norethindrone terminal half-life is approximately 7-10 hours. Steady-state is reached within 5-10 days. |
| Protein binding | Ethinyl estradiol: ~97-98% bound, primarily to albumin (70%) and sex hormone-binding globulin (SHBG). Norethindrone: ~61-63% bound, primarily to albumin and SHBG. |
| Volume of Distribution | Ethinyl estradiol: Vd approximately 2.5-4 L/kg; norethindrone: Vd approximately 4-5 L/kg. Distribution into breast milk and body fat is notable. |
| Bioavailability | Ethinyl estradiol: ~40-50% due to first-pass metabolism; norethindrone: ~50-65% with first-pass metabolism. Food may increase bioavailability. |
| Onset of Action | Oral administration: Contraceptive effect requires daily dosing; complete ovulation suppression occurs within 7 days if initiated on day 1 of menstrual cycle. |
| Duration of Action | Oral: Duration of contraceptive effect is 24 hours; requires daily dosing for maintenance. Missed dose increases pregnancy risk. |
One tablet orally once daily for 21 consecutive days, followed by 7 placebo tablets.
| Dosage form | TABLET |
| Renal impairment | Contraindicated in patients with renal impairment or renal disease. |
| Liver impairment | Contraindicated in patients with acute or chronic hepatic dysfunction (Child-Pugh class B or C). Use with caution in Child-Pugh class A, consider alternative therapy. |
| Pediatric use | Not indicated for use in pediatric females before menarche. For postmenarchal pediatric patients, dosage same as adults: one tablet orally once daily for 21 days, then 7 placebo tablets. |
| Geriatric use | Not indicated for use in postmenopausal women. Safety and efficacy not established in geriatric population. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for LARIN FE 1.5/30 (LARIN FE 1.5/30).
| Breastfeeding | Small amounts of ethinyl estradiol and norethindrone pass into breast milk; M/P ratio not established. May reduce milk quantity and quality. Not recommended for breastfeeding mothers until weaning complete to avoid infant exposure to sex hormones. |
| Teratogenic Risk | No increased risk of birth defects observed with oral contraceptives; avoid use in pregnancy due to potential for fetal harm and lack of necessity. First trimester: no consistent evidence of malformations. Second/third trimester: may cause fetal harm from estrogenic effects; discontinue if pregnancy occurs. |
■ FDA Black Box Warning
Cigarette smoking increases risk of serious cardiovascular events (stroke, myocardial infarction, thromboembolism) from combined oral contraceptives. Risk increases with age and number of cigarettes smoked, particularly in women >35 years. Advise not to smoke.
| Serious Effects |
Current or history of venous thromboembolism, arterial thrombosis, stroke, myocardial infarction, or transient ischemic attack; known coagulation disorders; valvular heart disease with complications; uncontrolled hypertension; diabetes with vascular involvement; headache with focal neurological symptoms (migraine with aura) in women >35; estrogen-sensitive cancer (e.g., breast cancer); hepatic tumors or active liver disease; undiagnosed abnormal uterine bleeding; pregnancy; hypersensitivity to components; cigarette smoking in women >35 years; use with hepatitis C drug regimens containing ombitasvir/paritaprevir/ritonavir (with or without dasabuvir).
| Precautions | Increased risk of venous thromboembolism, arterial thrombosis, stroke, myocardial infarction, especially in smokers >35 years, hypertension, obesity, diabetes, hyperlipidemia, or migraine with aura. Monitor for undiagnosed abnormal genital bleeding, liver disease, hypertension, depression, migraine, carbohydrate/lipid effects, hereditary angioedema, chloasma, retinal thrombosis, gallbladder disease, and anaphylactic reactions. Discontinue if jaundice, vision changes, or severe headache occurs. |
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| Fetal Monitoring | Monitor blood pressure, glucose, liver function, and signs of thromboembolism. In pregnancy, perform fetal ultrasound to assess growth if inadvertent exposure occurs. |
| Fertility Effects | Transiently inhibits ovulation; after discontinuation, return to fertility may be delayed but no long-term adverse effects on fertility. |