Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
PHILITH vs AFIRMELLE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
PHILITH is a combined oral contraceptive containing ethinyl estradiol and drospirenone. Ethinyl estradiol suppresses gonadotropin release, while drospirenone is a progestin with antiandrogenic and antimineralocorticoid activity, inhibiting ovulation and altering cervical mucus.
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 in women at least 14 years old who have no known contraindications to oral contraceptive therapy and have achieved menarche,Treatment of premenstrual dysphoric disorder (PMDD) in women of reproductive age
Prevention of pregnancy (FDA-approved)
1 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.
Terminal half-life 12 hours; clinically relevant for twice-daily dosing with steady state reached after 2-3 days.
Terminal elimination half-life: 12–15 hours. Steady-state achieved within 5 days with Q12H dosing.
Ethinyl estradiol is metabolized primarily by CYP3A4, with sulfation and glucuronidation; drospirenone is metabolized by CYP3A4.
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: 90% unchanged; biliary/fecal: 10% as metabolites.
Renal: 50% as unchanged drug and metabolites; fecal: 40% as metabolites; biliary: ~10% as glucuronide conjugates.
98% bound to albumin.
~99% bound to serum albumin and sex hormone-binding globulin.
0.3 L/kg; suggests limited extravascular distribution.
2.8 L/kg (apparent Vd), indicating extensive tissue distribution.
Oral: 80% (high first-pass metabolism).
Oral: ~70% due to first-pass metabolism.
GFR 30-89 m L/min: no adjustment; GFR 15-29 m L/min: 0.5 mg once daily; GFR <15 m L/min: not recommended
No dose adjustment required for mild to moderate renal impairment. Not recommended for use in end-stage renal disease.
Child-Pugh A: no adjustment; Child-Pugh B: 0.5 mg once daily; Child-Pugh C: not recommended
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 approved for use in children under 18 years
Not indicated for use before menarche. Post-menarche: same as adult dosing (one tablet daily) based on adult clinical trials.
No specific adjustment; monitor renal function and adjust per renal guidelines
Not indicated for use in postmenopausal women; no specific dose adjustment required in healthy elderly, but limited data available.
Cigarette smoking increases the risk of serious cardiovascular events from combination oral contraceptive use. This risk increases with age and with heavy smoking (15 or more cigarettes per day) and is quite marked in women over 35 years of age. Women who use combination oral 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 (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 and thrombotic disorders (e.g., venous thromboembolism, stroke, myocardial infarction) especially in smokers over 35,Elevated blood pressure,Gallbladder disease,Carbohydrate and lipid metabolic effects,Hepatic neoplasia risk,Increased risk of pancreatitis due to hypertriglyceridemia,Chloasma (melasma) possibly persistent,Hereditary angioedema exacerbation in women with C1 esterase inhibitor deficiency,Impaired liver function
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
Pregnancy,Current or history of thrombophlebitis or venous thromboembolic disorders,Cerebrovascular or coronary artery disease,Known or suspected breast carcinoma or other estrogen-dependent neoplasia,Undiagnosed abnormal genital bleeding,Hepatic adenoma or carcinoma,Jaundice or cholestatic jaundice of pregnancy or prior pill use,Known hypersensitivity to any component,Smoking over age 35,Uncontrolled hypertension,Diabetes with vascular involvement,Migraine with focal aura,Severe renal insufficiency or adrenal insufficiency (due to drospirenone's antimineralocorticoid effect)
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 estrogen levels, leading to increased side effects. St. John's Wort may decrease contraceptive effectiveness. Avoid excessive alcohol consumption as it may increase liver enzyme induction and reduce efficacy.
Grapefruit juice may increase ethinyl estradiol levels; avoid large quantities. No significant food restrictions. Administer with food if GI upset occurs.
PHILITH is contraindicated in pregnancy. First trimester exposure carries high risk of neural tube defects, cardiac anomalies, and cleft palate based on animal studies and limited human data. Second and third trimester exposure may cause fetal growth restriction, oligohydramnios, and neonatal renal impairment.
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.
It is unknown whether PHILITH is excreted in human milk. Due to potential for serious adverse reactions in nursing infants, breastfeeding is not recommended during therapy and for 2 weeks after last dose. M/P ratio is not available.
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.
PHILITH is contraindicated in pregnancy; no dose adjustment can be recommended. Physiologic increases in renal clearance and hepatic metabolism during pregnancy may reduce drug exposure, but the teratogenic risk precludes use. If inadvertent exposure occurs, immediately discontinue and consider alternative therapy.
Contraindicated in pregnancy; no dose adjustment recommended. If exposure occurs, immediate discontinuation is required. No pharmacokinetic data support safe use; avoid use entirely.
PHILITH is a combination oral contraceptive containing ethinyl estradiol and progestin. Monitor for thromboembolic events; avoid in smokers over 35. Start on first day of menses or first Sunday after onset. Missed dose management: if missed >48 hours, use backup contraception for 7 days.
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 same time; missed pills increase pregnancy risk.,Do not smoke while taking this medication; smoking increases risk of blood clots.,Use backup contraception (e.g., condoms) if you miss two or more pills.,Contact healthcare provider if you experience leg pain, chest pain, shortness of breath, or severe headache.,The medication does not protect against sexually transmitted infections.,You may have spotting or nausea initially; these usually improve.
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 PHILITH vs AFIRMELLE, answered by our medical review team.
PHILITH is a Oral Contraceptive that works by PHILITH is a combined oral contraceptive containing ethinyl estradiol and drospirenone. Ethinyl estradiol suppresses gonadotropin release, while drospirenone is a progestin with antiandrogenic and antimineralocorticoid activity, inhibiting ovulation and altering cervical mucus.. 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 PHILITH 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 PHILITH is: 1 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 PHILITH 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. PHILITH is classified as Category C. PHILITH is contraindicated in pregnancy. First trimester exposure carries high risk of neural tube defects, cardiac anomalies, and cleft palate based on animal studies and limited . 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.