Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
OGESTREL 0.5/50-28 vs AFIRMELLE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Combination estrogen-progestin contraceptive; suppresses gonadotropins (FSH, LH) via negative feedback on hypothalamic-pituitary axis, inhibiting ovulation; increases cervical mucus viscosity and alters endometrial development.
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.
Prevention of pregnancy,Treatment of moderate acne vulgaris (females ≥15 years, for formulations with at least 30 mcg ethinyl estradiol and norgestimate/desogestrel)
Prevention of pregnancy (FDA-approved)
One tablet (norgestrel 0.5 mg/ethinyl estradiol 50 mcg) orally once daily for 28-day cycle.
One tablet (0.1 mg levonorgestrel, 0.02 mg ethinyl estradiol) orally once daily for 21 days, followed by 7 days of placebo.
Norgestrel: ~45 hours (range 24-56 h) enabling once-daily dosing; Ethinyl estradiol: ~17 hours (range 10-27 h).
Terminal elimination half-life: 12–15 hours. Steady-state achieved within 5 days with Q12H dosing.
Norgestrel and ethinyl estradiol are metabolized primarily via cytochrome P450 3A4 (CYP3A4) in the liver; undergo first-pass metabolism; ethinyl estradiol also undergoes conjugation (sulfation, glucuronidation).
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.
Renal: 50-60% as metabolites (glucuronide and sulfate conjugates of norgestrel and ethinyl estradiol); Fecal: 30-40% via biliary elimination; Unchanged drug: <1%.
Renal: 50% as unchanged drug and metabolites; fecal: 40% as metabolites; biliary: ~10% as glucuronide conjugates.
Norgestrel: ~97% bound to sex hormone-binding globulin (SHBG) and albumin; Ethinyl estradiol: ~98% bound to albumin, with 2% free (active).
~99% bound to serum albumin and sex hormone-binding globulin.
Norgestrel: ∼4 L/kg (range 3-5 L/kg), indicating extensive tissue distribution; Ethinyl estradiol: ∼2 L/kg (range 1.5-3 L/kg), reflecting distribution to reproductive tissues and liver.
2.8 L/kg (apparent Vd), indicating extensive tissue distribution.
Oral: Norgestrel ~90-100% (high first-pass metabolism but minimal systemic loss); Ethinyl estradiol ~40-50% due to first-pass metabolism (conjugation in gut wall and liver).
Oral: ~70% due to first-pass metabolism.
No dose adjustment required for mild to moderate renal impairment. Not recommended in severe renal impairment (Cr Cl <30 m L/min) or ESRD due to lack of safety data.
No dose adjustment required for mild to moderate renal impairment. Not recommended for use in end-stage renal disease.
Contraindicated in acute hepatic disease or Child-Pugh class B and C cirrhosis. For mild hepatic impairment (Child-Pugh A), use with caution; no specific dose adjustment studied.
Contraindicated in acute hepatic disease or severe (Child-Pugh C) hepatic impairment. Use with caution in mild to moderate hepatic impairment; monitor liver function.
Not indicated for children; use only after menarche. Postmenarcheal adolescents: same as adult dosing (one tablet daily) once menses established.
Not indicated for use before menarche. Post-menarche: same as adult dosing (one tablet daily) based on adult clinical trials.
Not indicated for women ≥65 years; no geriatric-specific dosing recommended. Consider alternative therapies due to increased thrombosis risk and reduced bone density with prolonged use.
Not indicated for use in postmenopausal women; no specific dose adjustment required in healthy elderly, but limited data available.
Cigarette smoking increases risk of serious cardiovascular events from combination oral contraceptives. Risk increases with age (>35 years) and number of cigarettes smoked. Women over 35 who smoke should not use this product.
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.
Thrombotic disorders (venous thromboembolism, arterial thromboembolism, stroke, MI),Cerebrovascular disease,Hepatic neoplasia,Gallbladder disease,Hypertension,Carbohydrate/lipid effects,Headache/migraine,Vaginal bleeding irregularities,Depression,Hereditary angioedema
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
Known or suspected pregnancy,Current or history of venous thromboembolism (VTE) or arterial thromboembolism (ATE),Active liver disease or hepatic tumors,Undiagnosed abnormal genital bleeding,Known or suspected breast cancer or other estrogen-sensitive neoplasia,Hypersensitivity to any component,Cigarette smoking in women >35 years,Uncontrolled hypertension,Migraine with aura in women ≥35 years
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
No significant food interactions. Grapefruit juice may increase estrogen levels, but clinically negligible. Avoid high-fat meals if taking with a progestin-only pill (not applicable here).
Grapefruit juice may increase ethinyl estradiol levels; avoid large quantities. No significant food restrictions. Administer with food if GI upset occurs.
No increased risk of birth defects has been observed in clinical studies for norgestrel/ethinyl estradiol. Use during pregnancy is contraindicated as hormonal contraceptives are not indicated during gestation. There is no evidence of teratogenicity when inadvertently taken during early pregnancy.
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.
Small amounts of norgestrel and ethinyl estradiol are excreted in breast milk. M/P ratio not established. Can reduce milk production and quality. Use is generally not recommended during breastfeeding; alternative methods should be considered.
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.
Not applicable; contraindicated in pregnancy. No pharmacokinetic studies during pregnancy; no dose adjustment recommendation exists.
Contraindicated in pregnancy; no dose adjustment recommended. If exposure occurs, immediate discontinuation is required. No pharmacokinetic data support safe use; avoid use entirely.
OGESTREL 0.5/50-28 contains norgestrel 0.5 mg and ethinyl estradiol 50 mcg. Its higher estrogen dose (50 mcg) increases thromboembolic risk; avoid in smokers over 35. Use as emergency contraception off-label. Missed pill management: if one pill missed, take as soon as remembered; if two or more missed, use backup contraception. Withdrawal bleeding typically occurs during the 7 placebo pills.
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.
Take one pill daily at the same time; do not skip doses.,During the 7 placebo pills, you will have a withdrawal bleed; this is normal.,Use backup contraception (e.g., condoms) if you miss 2 or more pills.,Do not smoke while taking this medication, especially if over age 35.,Report any signs of blood clots: leg pain/swelling, chest pain, shortness of breath, sudden headache or vision changes.,This medication does not protect against HIV or other sexually transmitted infections.
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.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about OGESTREL 0.5/50-28 vs AFIRMELLE, answered by our medical review team.
OGESTREL 0.5/50-28 is a Oral Contraceptive that works by Combination estrogen-progestin contraceptive; suppresses gonadotropins (FSH, LH) via negative feedback on hypothalamic-pituitary axis, inhibiting ovulation; increases cervical mucus viscosity and alters endometrial development.. AFIRMELLE is a Combined Oral Contraceptive that works by 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.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between OGESTREL 0.5/50-28 and AFIRMELLE depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of OGESTREL 0.5/50-28 is: One tablet (norgestrel 0.5 mg/ethinyl estradiol 50 mcg) orally once daily for 28-day cycle.. The standard adult dose of AFIRMELLE is: One tablet (0.1 mg levonorgestrel, 0.02 mg ethinyl estradiol) orally once daily for 21 days, followed by 7 days of placebo.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between OGESTREL 0.5/50-28 and AFIRMELLE in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. OGESTREL 0.5/50-28 is classified as Category C. No increased risk of birth defects has been observed in clinical studies for norgestrel/ethinyl estradiol. Use during pregnancy is contraindicated as hormonal contraceptives are no. AFIRMELLE is classified as Category C. Pregnancy category X. Contraindicated in pregnancy due to risk of fetal harm. First trimester: exposure associated with congenital anomalies (e.g., cardiovascular, neural tube defe. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.