Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
BRAVELLE vs ESTROSTEP 21
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Bravelle (urofollitropin) is a purified preparation of follicle-stimulating hormone (FSH) that stimulates ovarian follicular growth and maturation by binding to FSH receptors on granulosa cells, increasing c AMP production and promoting follicular development.
Estrostep 21 is a combination oral contraceptive containing ethinyl estradiol and norethindrone acetate. It works primarily by suppressing gonadotropin-releasing hormone (Gn RH) from the hypothalamus, reducing luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion from the pituitary, thereby inhibiting ovulation. Additionally, it thickens cervical mucus to impede sperm penetration and alters the endometrium to reduce implantation likelihood.
Ovulation induction in anovulatory women with polycystic ovary syndrome (PCOS),Controlled ovarian hyperstimulation for assisted reproductive technologies (ART) such as in vitro fertilization (IVF)
Prevention of pregnancy,Treatment of moderate acne vulgaris in females >= 15 years of age who have achieved menarche, are not pregnant, and desire oral contraception
For ovulation induction: 150 IU subcutaneously or intramuscularly once daily for 5 days, starting on day 3 or 5 of menstrual cycle. For controlled ovarian hyperstimulation: 150-225 IU subcutaneously or intramuscularly once daily for 5-7 days, then adjust based on response.
One tablet orally once daily for 21 days, each tablet contains norethindrone acetate 1 mg and ethinyl estradiol 20 mcg.
Terminal elimination half-life approximately 5-6 hours in healthy adults. Extended in renal impairment (up to 24 hours with Cr Cl <30 m L/min).
Ethinyl estradiol: 13-27 hours (terminal); norethindrone acetate: 5-14 hours (terminal). Steady-state achieved within 3-5 days.
Primarily metabolized in the liver via renal excretion; metabolic pathways not fully characterized.
Ethinyl estradiol is metabolized primarily via CYP3A4 and undergoes glucuronidation and sulfation. Norethindrone acetate is deacetylated to norethindrone, which is metabolized by CYP3A4 and other CYP enzymes, and undergoes reduction and glucuronidation.
Primarily renal: 95% of administered dose excreted unchanged in urine within 24 hours. Biliary/fecal: 5% eliminated via feces.
Biliary/fecal (40-50% as metabolites) and renal (30-40% as glucuronide and sulfate conjugates)
Approximately 10-20% bound to plasma proteins (albumin and α-1 acid glycoprotein).
Ethinyl estradiol: 97-98% bound to albumin; norethindrone: 95-97% bound to albumin and SHBG.
Approximately 0.3-0.5 L/kg. Distributing primarily in extracellular fluid; does not extensively penetrate tissues.
Ethinyl estradiol: 2.5-4.5 L/kg; norethindrone: 3.5-5.5 L/kg. Indicates extensive tissue distribution.
Subcutaneous: 90-95% bioavailable relative to intramuscular route. Oral: not clinically used due to enzymatic degradation.
Ethinyl estradiol: 38-48% (oral, first-pass metabolism); norethindrone acetate: 50-70% (oral, deacetylation to norethindrone).
No specific guidelines exist for GFR-based dose modifications; use with caution in severe renal impairment (Cr Cl <30 m L/min) and monitor for adverse effects.
No dose adjustment required for mild to moderate renal impairment. Contraindicated in severe renal impairment or acute renal failure.
No specific guidelines exist for Child-Pugh based modifications; use with caution in severe hepatic impairment and monitor for adverse effects.
Contraindicated in acute hepatitis, severe cirrhosis, benign or malignant liver tumors, or Child-Pugh class C cirrhosis. Use with caution in Child-Pugh class A or B; consider alternative therapy.
Not indicated for use in pediatric patients; safety and efficacy not established.
Not indicated for use before menarche. Post-menarche: same dosing as adults; use lowest effective dose for shortest duration.
Not indicated for use in geriatric patients; safety and efficacy not established.
Not indicated for postmenopausal women; no established dosing in elderly. Consider alternative therapies as necessary.
Bravelle should only be used by physicians who are experienced in infertility treatment and can manage potential serious adverse events, including ovarian hyperstimulation syndrome (OHSS) and multiple gestations.
Cigarette smoking increases the risk of serious cardiovascular events from oral contraceptive use. This risk increases with age (especially in women > 35 years) and with the number of cigarettes smoked. Women who use oral contraceptives should be strongly advised not to smoke.
Ovarian enlargement and ovarian hyperstimulation syndrome (OHSS) – can lead to serious complications; discontinue treatment if OHSS is suspected.,Multiple gestations – increased risk of multiple births.,Ovarian torsion – report sudden abdominal pain.,Pulmonary and vascular complications – thromboembolic events; discontinue if suspected.,Ectopic pregnancy and spontaneous abortion – higher rates in ART patients.,Neoplasms – risk of ovarian neoplasms with repeated use.
Increased risk of thromboembolic disorders (e.g., venous thromboembolism, stroke, myocardial infarction), especially in smokers and women over 35,Hepatic neoplasia (benign and malignant) reported,Hypertension and gallbladder disease,Carbohydrate and lipid effects; monitor in diabetic patients,Ocular lesions (e.g., retinal thrombosis); discontinue if unexplained vision loss or proptosis occurs,Hereditary angioedema exacerbation,Chloasma; avoid sun exposure,Menstrual irregularities (e.g., breakthrough bleeding, amenorrhea),Depression; discontinue if severe
Hypersensitivity to urofollitropin or any component,High levels of FSH indicating primary ovarian failure,Uncontrolled thyroid or adrenal dysfunction,Known or suspected pregnancy,Ovarian cyst or enlargement of undetermined origin,Abnormal uterine bleeding of undetermined origin,Sex hormone-dependent tumors (e.g., breast, uterus, ovary)
Thrombophlebitis, thromboembolic disorders, or history thereof (e.g., deep vein thrombosis, pulmonary embolism),Cerebrovascular disease (e.g., stroke, TIA),Coronary artery disease (e.g., myocardial infarction, angina),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,Benign or malignant liver tumors,Known or suspected pregnancy,Hypersensitivity to any component,Smoking in women over 35 years of age
No known food interactions. Maintain normal diet and hydration. Avoid alcohol as it may exacerbate side effects like nausea.
No specific food interactions. Grapefruit juice may increase estrogen exposure (mild effect). Maintain consistent timing with meals to reduce nausea if needed. Avoid alcohol if liver function is compromised.
Pregnancy Category X. Urofollitropin is contraindicated in pregnant women due to risk of fetal harm. First trimester: Ovarian hyperstimulation syndrome (OHSS) and multiple gestations. Second and third trimesters: No direct fetal effects reported, but risks associated with multiple gestation (preterm birth, low birth weight). Maternal OHSS may lead to thromboembolism.
Estrostep 21 (norethindrone acetate/ethinyl estradiol) is contraindicated in pregnancy. First trimester: increased risk of cardiovascular malformations, limb reduction defects, and neural tube defects. Second and third trimesters: associated with fetal genital abnormalities, feminization of male fetuses, and potential long-term reproductive effects. Use in early pregnancy for emergency contraception is not recommended due to potential risks.
Urofollitropin is not indicated for use during lactation. No data on excretion in human milk, M/P ratio not established. Use during breastfeeding is contraindicated due to potential for adverse effects on infant hormone levels.
Estrostep 21 is excreted in breast milk in small amounts; ethinyl estradiol M/P ratio approximately 0.1; norethindrone M/P ratio ~0.5. May reduce milk production and quality, especially in early lactation. Use generally avoided during breastfeeding; consider progestin-only alternatives.
No dose adjustment applicable as therapy is discontinued upon confirmed pregnancy. No pharmacokinetic data during pregnancy; drug is not used after conception due to contraindication.
Estrostep 21 is contraindicated in pregnancy; no dose adjustments recommended as use is avoided. Pharmacokinetic changes during pregnancy (increased hepatic metabolism, volume of distribution) would require dose adjustment if used, but due to risks, alternative therapy is indicated.
BRAVELLE (urofollitropin) is a purified FSH product used for controlled ovarian hyperstimulation. Administer subcutaneously; rotate injection sites. Monitor estradiol levels and follicle growth via ultrasound. Risk of ovarian hyperstimulation syndrome (OHSS); consider using Gn RH antagonist protocols to reduce risk. Do not administer if patient has high baseline FSH levels (>15 IU/L) indicating poor ovarian reserve.
ESTROSTEP 21 is a monophasic oral contraceptive containing norethindrone acetate and ethinyl estradiol. Due to its low estrogen dose (20 mcg), it may be associated with more breakthrough bleeding compared to higher-dose pills. It is indicated for contraception and may be used for acne treatment. The 21-day regimen requires a 7-day hormone-free interval. Counsel patients that smoking increases the risk of serious cardiovascular adverse effects; avoid in women over 35 who smoke.
Teach proper injection technique and site rotation (abdomen, thigh).,Report immediately if severe pelvic pain, nausea, vomiting, or rapid weight gain occurs (OHSS signs).,Avoid intercourse until instructed to prevent multiple pregnancy.,Inform of multiple pregnancy risk (especially twins).,Store vials in refrigerator (2-8°C) and protect from light.
Take one tablet daily at the same time each day for 21 days, then no pills for 7 days.,If you miss a dose, follow the package instructions; use backup contraception if missed more than one tablet.,Do not smoke while taking this medication; smoking increases risk of blood clots, stroke, and heart attack, especially if over 35.,Common side effects include spotting, nausea, breast tenderness, and headache; these often improve after a few cycles.,Seek emergency care if you have signs of a blood clot: sudden leg pain, chest pain, shortness of breath, or vision changes.,This medication does not protect against HIV or other sexually transmitted infections.,Take missed pills as soon as remembered; do not take more than two tablets in one day.
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 BRAVELLE vs ESTROSTEP 21, answered by our medical review team.
BRAVELLE is a Gonadotropin that works by Bravelle (urofollitropin) is a purified preparation of follicle-stimulating hormone (FSH) that stimulates ovarian follicular growth and maturation by binding to FSH receptors on granulosa cells, increasing c AMP production and promoting follicular development.. ESTROSTEP 21 is a Combined Oral Contraceptive that works by Estrostep 21 is a combination oral contraceptive containing ethinyl estradiol and norethindrone acetate. It works primarily by suppressing gonadotropin-releasing hormone (Gn RH) from the hypothalamus, reducing luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion from the pituitary, thereby inhibiting ovulation. Additionally, it thickens cervical mucus to impede sperm penetration and alters the endometrium to reduce implantation likelihood.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between BRAVELLE and ESTROSTEP 21 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 BRAVELLE is: For ovulation induction: 150 IU subcutaneously or intramuscularly once daily for 5 days, starting on day 3 or 5 of menstrual cycle. For controlled ovarian hyperstimulation: 150-225 IU subcutaneously or intramuscularly once daily for 5-7 days, then adjust based on response.. The standard adult dose of ESTROSTEP 21 is: One tablet orally once daily for 21 days, each tablet contains norethindrone acetate 1 mg and ethinyl estradiol 20 mcg.. 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 BRAVELLE and ESTROSTEP 21 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. BRAVELLE is classified as Category C. Pregnancy Category X. Urofollitropin is contraindicated in pregnant women due to risk of fetal harm. First trimester: Ovarian hyperstimulation syndrome (OHSS) and multiple gestatio. ESTROSTEP 21 is classified as Category C. Estrostep 21 (norethindrone acetate/ethinyl estradiol) is contraindicated in pregnancy. First trimester: increased risk of cardiovascular malformations, limb reduction defects, and. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.