Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
PORTIA-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 oral contraceptive: estrogen (ethinyl estradiol) suppresses gonadotropin release, inhibiting ovulation; progestin (levonorgestrel) alters cervical mucus and endometrial lining.
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
Prevention of pregnancy (FDA-approved)
One tablet (levonorgestrel 0.15 mg, ethinyl estradiol 0.03 mg) orally once daily
One tablet (0.1 mg levonorgestrel, 0.02 mg ethinyl estradiol) orally once daily for 21 days, followed by 7 days of placebo.
Levonorgestrel: 24-30 hours; ethinyl estradiol: 12-15 hours. Clinical context: Steady-state achieved within 5-7 days.
Terminal elimination half-life: 12–15 hours. Steady-state achieved within 5 days with Q12H dosing.
Hepatic: ethinyl estradiol and levonorgestrel are metabolized via CYP3A4, conjugation, and sulfation.
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 (60-70% as metabolites, 20-30% as levonorgestrel/ethinyl estradiol glucuronides), fecal (10-20%), biliary (minor).
Renal: 50% as unchanged drug and metabolites; fecal: 40% as metabolites; biliary: ~10% as glucuronide conjugates.
Levonorgestrel: 97.5-99% to sex hormone-binding globulin (SHBG) and albumin; ethinyl estradiol: 98-99% to albumin.
~99% bound to serum albumin and sex hormone-binding globulin.
Levonorgestrel: 1.8 L/kg (extensive tissue distribution).
2.8 L/kg (apparent Vd), indicating extensive tissue distribution.
Oral: levonorgestrel ~100%, ethinyl estradiol ~40-45% (first-pass metabolism).
Oral: ~70% due to first-pass metabolism.
No dose adjustment required for mild to moderate renal impairment; contraindicated in severe renal disease
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 severe cirrhosis (Child-Pugh C); use with caution in mild to moderate hepatic impairment
Contraindicated in acute hepatic disease or severe (Child-Pugh C) hepatic impairment. Use with caution in mild to moderate hepatic impairment; monitor liver function.
Use only after menarche; dose as per adult schedule (one tablet daily)
Not indicated for use before menarche. Post-menarche: same as adult dosing (one tablet daily) based on adult clinical trials.
Not indicated for postmenopausal women
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 contraceptive use. Risk increases with age and heavy smoking (≥15 cigarettes/day). 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.
Increased risk of thromboembolic disorders (VTE, MI, stroke),Hepatic neoplasia,Hypertension,Gallbladder disease,Carbohydrate/lipid metabolism effects,Bleeding irregularities
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
Thrombophlebitis or thromboembolic disorders,Cerebrovascular or coronary artery disease,Known or suspected pregnancy,Undiagnosed abnormal genital bleeding,Known or suspected breast cancer,Liver tumors or active liver disease,Hypersensitivity to any component,Use with Hepatitis C drug combinations containing ombitasvir/paritaprevir/ritonavir with or without dasabuvir
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
Grapefruit and grapefruit juice may increase ethinyl estradiol levels and risk of adverse effects; avoid concurrent consumption. No other significant food interactions. Maintain consistent dietary habits as changes in diet may affect drug absorption. Do not consume alcohol excessively as it may increase risk of liver toxicity and reduce contraceptive efficacy.
Grapefruit juice may increase ethinyl estradiol levels; avoid large quantities. No significant food restrictions. Administer with food if GI upset occurs.
Pregnancy category X. Contraindicated in pregnancy. First trimester exposure associated with cardiovascular defects, neural tube defects, and limb reduction anomalies. Second and third trimester exposure may cause fetal adrenal suppression, virilization of female fetuses due to progestin component, and potential long-term neurodevelopmental effects. Postnatal effects include possible behavioral issues.
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.
Excreted into breast milk. M/P ratio not well established; progestins and estrogens are present in low levels. Potential for adverse effects on infant such as jaundice and breast enlargement. Generally not recommended during breastfeeding; alternative contraception advised.
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 dose adjustment recommendations exist as use is contraindicated.
Contraindicated in pregnancy; no dose adjustment recommended. If exposure occurs, immediate discontinuation is required. No pharmacokinetic data support safe use; avoid use entirely.
Portia-28 is a combination oral contraceptive (COC) containing ethinyl estradiol and levonorgestrel. Initiate on the first day of menstrual bleeding or the first Sunday after onset; if starting after day 5, use backup contraception for 7 days. Missed pill management: if one pill is missed, take it as soon as remembered and continue regular schedule (may take two pills in one day); if two or more pills are missed, take the most recent missed pill, discard others, use backup contraception for 7 days, and consider emergency contraception if unprotected intercourse occurred. Maximum efficacy requires daily adherence at the same time. CYP3A4 inducers (e.g., rifampin, St. John's wort) may reduce contraceptive effectiveness; consider alternative non-hormonal methods during co-administration. Portia-28 may increase serum potassium; caution with potassium-sparing diuretics, ACE inhibitors, or ARBs. Discontinue if migraines with aura, unexplained visual loss, or signs of thromboembolism occur. Monitor blood pressure and liver function periodically.
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 tablet daily at the same time each day, with or without food. Do not skip doses.,If you miss a pill, refer to the missed pill instructions in the package insert; use backup contraception if needed.,Portia-28 does not protect against HIV or other sexually transmitted infections; use condoms for STI prevention.,Smoking increases risk of serious cardiovascular events; avoid smoking, especially if over age 35.,Contact your healthcare provider immediately if you experience chest pain, shortness of breath, leg swelling, severe headache, vision changes, or jaundice.,Inform your doctor of all medications you take, including over-the-counter drugs and herbal supplements.,Store at room temperature away from moisture and heat; keep out of reach of children.
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 PORTIA-28 vs AFIRMELLE, answered by our medical review team.
PORTIA-28 is a Oral Contraceptive that works by Combination oral contraceptive: estrogen (ethinyl estradiol) suppresses gonadotropin release, inhibiting ovulation; progestin (levonorgestrel) alters cervical mucus and endometrial lining.. 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 PORTIA-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 PORTIA-28 is: One tablet (levonorgestrel 0.15 mg, ethinyl estradiol 0.03 mg) orally once daily. 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 PORTIA-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. PORTIA-28 is classified as Category C. Pregnancy category X. Contraindicated in pregnancy. First trimester exposure associated with cardiovascular defects, neural tube defects, and limb reduction anomalies. Second and t. 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.