Comparative Pharmacology
Head-to-head clinical analysis: AFIRMELLE versus LOESTRIN FE 1 5 30.
Peer-Reviewed Evidence
Head-to-head clinical analysis: AFIRMELLE versus LOESTRIN FE 1 5 30.
AFIRMELLE vs LOESTRIN FE 1.5/30
Head-to-head clinical comparison of therapeutic indices and safety profiles.
Combination oral contraceptive containing ethinyl estradiol and levonorgestrel. Inhibits ovulation by suppressing gonadotropin release (FSH and LH). Also increases cervical mucus viscosity and alters endometrial receptivity.
Suppresses gonadotropin (FSH and LH) release via estrogen and progestin feedback inhibition, preventing ovulation; increases cervical mucus viscosity and alters endometrial lining.
Prevention of pregnancy (FDA-approved)
Prevention of pregnancyTreatment of heavy menstrual bleeding (off-label)Treatment of dysmenorrhea (off-label)Treatment of acne (off-label)
One tablet (0.1 mg levonorgestrel, 0.02 mg ethinyl estradiol) orally once daily for 21 days, followed by 7 days of placebo.
One tablet orally once daily at the same time each day for 21 consecutive days, followed by 7 days of placebo (ferrous fumarate) tablets, then restart.
None Documented
None Documented
Terminal elimination half-life: 12–15 hours. Steady-state achieved within 5 days with Q12H dosing.
Norethindrone: ~5-14 hours (terminal); Ethinyl estradiol: ~13-27 hours (terminal). Clinically, steady-state achieved within 5-7 days.
Ethinyl estradiol undergoes first-pass metabolism in gut and liver via CYP3A4, with conjugation to sulfate and glucuronide. Levonorgestrel is metabolized primarily by CYP3A4 to reduced and hydroxylated metabolites, then conjugated.
Metabolized in liver via CYP3A4 (norethindrone) and hydroxylation/conjugation (ethinyl estradiol).
Renal: 50% as unchanged drug and metabolites; fecal: 40% as metabolites; biliary: ~10% as glucuronide conjugates.
Renal: ~50-60% (norethindrone metabolites); Fecal: ~20-30% (norethindrone); Ethinyl estradiol: primarily renal (~40-50%) and fecal (~20-50%) as glucuronide and sulfate conjugates.
~99% bound to serum albumin and sex hormone-binding globulin.
Norethindrone: ~80-90% bound to SHBG and albumin; Ethinyl estradiol: ~95-98% bound primarily to albumin (with some to SHBG).
2.8 L/kg (apparent Vd), indicating extensive tissue distribution.
Norethindrone: ~4 L/kg; Ethinyl estradiol: ~4-10 L/kg; indicates extensive tissue distribution.
Oral: ~70% due to first-pass metabolism.
Oral: Norethindrone ~64%; Ethinyl estradiol ~38-48% (due to first-pass metabolism).
No dose adjustment required for mild to moderate renal impairment. Not recommended for use in end-stage renal disease.
No dose adjustment required for renal impairment; however, use with caution in patients with impaired renal function due to potential fluid retention.
Contraindicated in acute hepatic disease or severe (Child-Pugh C) hepatic impairment. Use with caution in mild to moderate hepatic impairment; monitor liver function.
Contraindicated in acute hepatic disease or liver tumors (benign or malignant). For Child-Pugh Class A, no dose adjustment; avoid use in Class B or C.
Not indicated for use before menarche. Post-menarche: same as adult dosing (one tablet daily) based on adult clinical trials.
Not indicated for use before menarche. For postmenarchal adolescents, same dosing as adults: one tablet orally once daily.
Not indicated for use in postmenopausal women; no specific dose adjustment required in healthy elderly, but limited data available.
Not indicated for use in postmenopausal women. No specific geriatric dosing.
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptive use. Risk increases with age (especially in women over 35) and with heavy smoking (15+ cigarettes/day). Women who use combination hormonal contraceptives should be strongly advised not to smoke.
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptive use; risk increases with age and heavy smoking (≥15 cigarettes/day) and is significant in women over 35. Women who use combination oral contraceptives should be strongly advised not to smoke.
["Thrombotic disorders (venous thromboembolism, stroke, myocardial infarction)","Cigarette smoking (increases cardiovascular risk)","Hypertension (especially in women with renal disease or migraines)","Gallbladder disease","Hepatic neoplasia (benign and malignant)","Carbohydrate and lipid metabolism effects","Ocular lesions (retinal thrombosis)","Depressed mood or depression","Uterine bleeding irregularities","Reduced efficacy with hepatic enzyme inducers"]
Increased risk of thromboembolic events; cardiovascular disease; hypertension; gallbladder disease; hepatic neoplasia; elevated liver enzymes; possible increased risk of breast/cervical cancer; glucose intolerance; fluid retention; hereditary angioedema; chloasma; irregular bleeding; depression; contact lens intolerance; possible reduced efficacy with enzyme-inducing drugs.
["Thrombophlebitis or thromboembolic disorders (current or history)","Cerebrovascular or coronary artery disease (current or history)","Known or suspected breast cancer, endometrial cancer, or other estrogen-dependent neoplasia","Undiagnosed abnormal genital bleeding","Cholestatic jaundice of pregnancy or jaundice with prior oral contraceptive use","Hepatic adenoma or carcinoma (current or history)","Known or suspected pregnancy","Hypersensitivity to any component of the product","Heavy smoking (≥15 cigarettes/day) in women over 35"]
Thrombophlebitis or thromboembolic disorders; history of deep vein thrombosis or pulmonary embolism; cerebrovascular or coronary artery disease; known or suspected breast carcinoma; carcinoma of endometrium or other estrogen-dependent neoplasia; undiagnosed abnormal genital bleeding; cholestatic jaundice of pregnancy or jaundice with prior oral contraceptive use; hepatic adenoma or carcinoma; known or suspected pregnancy; hypersensitivity to any component; current or history of migraine with aura (age ≥35); heavy smoking (≥15 cigarettes/day) in women ≥35 years; uncontrolled hypertension; diabetes with vascular involvement; major surgery with prolonged immobilization; known thrombophilic conditions.
Data Pending Review
Data Pending Review
Grapefruit juice may increase ethinyl estradiol levels; avoid large quantities. No significant food restrictions. Administer with food if GI upset occurs.
No significant food interactions. Grapefruit juice may slightly increase ethinyl estradiol levels but not clinically relevant. Separate iron tablets from high-calcium foods or supplements (e.g., dairy) to enhance iron absorption, but this does not affect contraceptive efficacy.
Pregnancy category X. Contraindicated in pregnancy due to risk of fetal harm. First trimester: exposure associated with congenital anomalies (e.g., cardiovascular, neural tube defects). Second and third trimesters: increased risk of fetal growth restriction, preterm birth, and neonatal respiratory distress. Postnatal: possible long-term developmental effects.
FDA Pregnancy Category X. Use contraindicated in pregnancy. First trimester: increased risk of neural tube defects, cardiovascular anomalies, and limb reduction defects. Second and third trimesters: associated with fetal harm, including masculinization of female fetuses due to progestin component. No safe use during pregnancy.
Contraindicated during breastfeeding. Small amounts of ethinyl estradiol and norethindrone are excreted in breast milk; M/P ratio not well defined. Potential for adverse effects on infant (e.g., jaundice, breast enlargement). May reduce milk production and quality.
Small amounts of ethinyl estradiol and norethindrone acetate excreted in breast milk; M/P ratio not reported. May reduce milk production and quality. Use only if clearly needed; lowest effective dose recommended. Caution in nursing mothers.
Contraindicated in pregnancy; no dose adjustment recommended. If exposure occurs, immediate discontinuation is required. No pharmacokinetic data support safe use; avoid use entirely.
Contraindicated in pregnancy; no dosing adjustment applicable. Discontinue immediately if pregnancy occurs.
Category C
Category C
Afirmelle (levonorgestrel/ethinyl estradiol) is a combined oral contraceptive. Counsel patients to take at the same time daily to maintain consistent hormone levels. Use back-up contraception if a dose is missed. Monitor for signs of thromboembolism, especially in smokers over 35. Advise that certain antibiotics (e.g., rifampin) and anticonvulsants (e.g., phenytoin) may reduce efficacy. Consider progestin-only pill if contraindications to estrogen exist.
Loestrin Fe 1.5/30 contains norethindrone acetate 1.5 mg and ethinyl estradiol 30 mcg plus ferrous fumarate (75 mg) as placebo pills. The iron supplement does not affect contraceptive efficacy. Be aware of increased risk of venous thromboembolism, especially in smokers over 35. Use with caution in patients with migraine with aura. Drug interactions with CYP3A4 inducers (e.g., rifampin, carbamazepine) may reduce efficacy. Breakthrough bleeding is common in first few cycles. Do not use in patients with hepatic impairment or known thrombophilia.
Take one pill at the same time every day, even if you don't have sex.If you miss a pill, follow the instructions in the package insert or ask your healthcare provider.Use a backup method (like condoms) if you start late or miss pills.This medication does not protect against HIV or other sexually transmitted infections.Common side effects include nausea, breast tenderness, and breakthrough bleeding.Seek medical help if you have symptoms of a blood clot: sudden chest pain, leg swelling, or shortness of breath.Smoking while on this pill increases your risk of serious cardiovascular events.
Take one tablet daily at the same time each day, starting on the first day of menstrual bleeding.The first 21 tablets are active hormones; the last 7 tablets are iron supplements that do not prevent pregnancy.Missed dose: if you miss one active tablet, take it as soon as remembered; no backup needed. If you miss two, take two tablets and use backup contraception for 7 days.Iron tablets may cause dark stools; this is harmless.Report symptoms of blood clots: sudden leg pain, chest pain, shortness of breath, or severe headache.Use additional contraception if starting within 5 days of stopping another hormonal contraceptive.Avoid smoking while on this medication, especially if over 35.