Levonorgestrel-Ethinyl Estradiol

• Contraception (Birth Control)
• Pregnancy Prevention
• Acne Treatment (some formulations)
• Menstrual Regulation

Levonorgestrel/ethinyl estradiol is a combination oral contraceptive containing a progestin and an estrogen, used for the prevention of pregnancy. This widely prescribed contraceptive is available in various formulations and provides reliable birth control when taken correctly.

Mechanism of Action

The combination of levonorgestrel and ethinyl estradiol prevents pregnancy through multiple mechanisms. The primary mechanism is suppression of gonadotropins (FSH and LH), which inhibits ovulation. Levonorgestrel, the progestin component, primarily suppresses the LH surge necessary for ovulation. Additionally, the hormones cause changes to the cervical mucus, making it hostile to sperm penetration, and alterations to the endometrium that may reduce the likelihood of implantation. The estrogen component (ethinyl estradiol) contributes to ovulation suppression and helps stabilize the endometrium, preventing breakthrough bleeding.

Available Formulations

Levonorgestrel/ethinyl estradiol is available in numerous brand and generic formulations with varying doses and regimens: monophasic (same dose throughout cycle), biphasic, and triphasic (varying doses). Common formulations include 21/7 regimens (21 active pills, 7 placebo) and extended-cycle regimens (84 active pills). Doses of ethinyl estradiol range from 20-35 mcg; levonorgestrel doses vary from 0.05-0.15 mg.

Medical Uses

Levonorgestrel/ethinyl estradiol is FDA-approved for prevention of pregnancy. Some formulations are also approved for treatment of acne vulgaris in females at least 15 years of age who desire contraception. Off-label uses include management of dysmenorrhea, menorrhagia, endometriosis, and premenstrual syndrome. Extended-cycle formulations are used to reduce menstrual frequency.

Dosing Guidelines

Take one tablet daily at the same time each day, as directed for the specific product. Most formulations are taken for 21 days followed by 7 days of placebo (or hormone-free interval). Extended-cycle products have different schedules. Start timing varies: Sunday start, Day 1 start, or quick start methods may be used. If a pill is missed, follow product-specific instructions; backup contraception may be needed.

Important Safety Information

Combination oral contraceptives carry a boxed warning that cigarette smoking increases the risk of serious cardiovascular side effects (MI, stroke, thromboembolism), especially in women over 35 who smoke heavily; women who smoke should not use combination oral contraceptives. Other serious risks include VTE, stroke, MI, hepatic tumors, gallbladder disease, hypertension, and carbohydrate/lipid metabolic effects. Contraindications include thrombophlebitis or thromboembolic disorders, history of DVT/PE, cerebrovascular disease, coronary artery disease, breast cancer, hepatic tumors, and undiagnosed abnormal uterine bleeding.

Drug Interactions

CYP3A4 inducers (rifampin, phenytoin, carbamazepine, St. John's Wort, some HIV medications) may decrease contraceptive efficacy; backup contraception may be needed. Ethinyl estradiol may increase levels of CYP3A4 substrates (cyclosporine). The contraceptive may decrease lamotrigine levels. Antibiotics (other than rifampin) generally do not significantly affect contraceptive efficacy, though some product labeling recommends backup contraception.

Special Populations

Combination oral contraceptives are contraindicated during pregnancy. They are not recommended during breastfeeding in the first 4-6 weeks postpartum (may decrease milk production); progestin-only methods are preferred. Safety and efficacy have been established in reproductive-age females. Women over 35 who smoke should not use combination oral contraceptives. No dose adjustment is needed for renal impairment. The medication should not be used in women with significant hepatic impairment.