What is Larin Fe 1/20 (norethindrone and ethinyl estradiol), a type of oral contraceptive?

Larin Fe 1/20 - Combined Oral Contraceptive

Larin Fe 1/20 is a combined oral contraceptive containing norethindrone (1 mg) and ethinyl estradiol (20 mcg) with ferrous fumarate tablets, used for pregnancy prevention and FDA-approved for acne treatment in women desiring contraception. 1

Medication Composition and Classification

Larin Fe 1/20 contains:

• 1 mg norethindrone (a first-generation progestin)
• 20 mcg ethinyl estradiol (a synthetic estrogen)
• Ferrous fumarate tablets (iron supplement during the placebo week)

This medication belongs to the class of combined oral contraceptives (COCs) that contain both estrogen and progestin components. The "1/20" in the name indicates the dosage of each hormone (1 mg norethindrone and 20 mcg ethinyl estradiol).

Mechanism of Action

Larin Fe 1/20 works through multiple mechanisms:

• Inhibits gonadotropin-releasing hormone, follicle-stimulating hormone, and luteinizing hormone, preventing ovulation 1
• Thickens cervical mucus to inhibit sperm penetration 2
• Slows ovum movement through fallopian tubes 2
• Alters the endometrium, making it less receptive to implantation 2

Effectiveness

• Highly effective for pregnancy prevention when used correctly
• The Pearl Index (pregnancy rate) for similar formulations is approximately 2.2 pregnancies per 100 woman-years 3
• Also effective for acne treatment due to its anti-androgenic properties 1

Non-Contraceptive Benefits

Larin Fe 1/20 offers several additional benefits:

• Treatment of acne vulgaris (FDA-approved indication) 1
• Decreases ovarian androgen production 1
• Increases sex hormone-binding globulin 1
• Reduces free testosterone 1
• Reduces 5α-reductase activity and blocks androgen receptors 1

Important Safety Considerations

Contraindications

This medication should not be used in women with:

• History of venous thromboembolism or arterial thrombotic disease
• Breast or endometrial carcinoma
• Undiagnosed abnormal genital bleeding
• Severe hypertension
• Diabetes with vascular involvement
• Migraine with aura
• Liver tumors
• Age ≥35 years who smoke 4

Risk of Venous Thromboembolism (VTE)

• Baseline VTE risk in non-users: 1 per 10,000 woman-years
• Risk with combined hormonal contraceptives: 3-4 per 10,000 woman-years 4
• The absolute risk of VTE with COC use is small compared to the risk during pregnancy (5-20 per 10,000 woman-years) 1

Drug Interactions

Effectiveness may be reduced when used with:

• Anticonvulsants
• Antimicrobials
• HIV protease inhibitors
• St. John's wort
• Other enzyme inducers 4, 5

Common Side Effects

• Headache
• Abdominal pain
• Breast tenderness
• Breakthrough bleeding/spotting, particularly in the first few cycles

Administration

• Taken once daily for 24 active hormone tablets, followed by 4 ferrous fumarate (iron) tablets
• The iron tablets help maintain the daily pill-taking routine while providing iron supplementation during the hormone-free interval

Larin Fe 1/20 represents a low-dose combined oral contraceptive option that balances effectiveness with a lower hormone dose to minimize side effects while providing both contraceptive protection and acne treatment benefits.