Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
OSPEMIFENE vs OSPHENA
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Ospemifene is a selective estrogen receptor modulator (SERM) that acts as an agonist on estrogen receptors in vaginal tissues, leading to proliferation and maturation of vaginal epithelium, while exhibiting antagonist activity on breast and endometrial tissues.
Selective estrogen receptor modulator (SERM) that acts as an estrogen agonist on bone and lipid metabolism, and as an estrogen antagonist on breast and uterine tissue. It mimics estrogen's effects on bone by reducing bone resorption and increasing bone mineral density.
Treatment of moderate to severe dyspareunia (painful intercourse) due to vulvar and vaginal atrophy associated with menopause
Treatment of osteoporosis in postmenopausal women at high risk of fracture,Reduction in risk of invasive breast cancer in postmenopausal women with osteoporosis,Reduction in risk of invasive breast cancer in postmenopausal women at high risk for invasive breast cancer
60 mg orally once daily.
60 mg orally once daily with food.
Terminal elimination half-life is approximately 26 hours (range 20–30 hours), supporting once-daily dosing.
The terminal elimination half-life of ospemifene is approximately 26 hours (range 22-39 hours), supporting once-daily dosing.
Primarily metabolized via CYP3A4 and CYP2C9, with minor contributions from CYP2C19, CYP2C8, and CYP2B6. Undergoes glucuronidation and sulfation.
Extensively metabolized in the liver via glucuronidation (UGT1A8, UGT1A10, UGT2B7) and to a lesser extent by cytochrome P450 (CYP3A4, CYP2C19). Undergoes enterohepatic recycling. Half-life is approximately 5.7 days.
Primarily hepatic metabolism with biliary excretion; < 30% renal elimination as metabolites. Fecal excretion accounts for approximately 70% of total clearance.
Following oral administration, 50% of a radiolabeled dose is excreted in urine and 35% in feces within 168 hours, primarily as glucuronide conjugates; <1% is excreted unchanged.
> 99% bound to serum proteins, primarily albumin.
Ospemifene is >99% bound to plasma proteins, primarily albumin.
Approximately 4.2 L/kg, indicating extensive tissue distribution.
The apparent volume of distribution (Vd/F) is approximately 2.4 L/kg, indicating extensive tissue distribution.
Oral bioavailability is approximately 20–30% due to first-pass metabolism.
Absolute bioavailability is approximately 30% after oral administration due to first-pass metabolism.
No dose adjustment required for mild to moderate renal impairment (Cr Cl ≥15 m L/min). Not studied in severe renal impairment (Cr Cl <15 m L/min) or dialysis.
No dose adjustment required for mild to moderate renal impairment; not studied in severe renal impairment (Cr Cl <30 m L/min).
Contraindicated in Child-Pugh Class C (severe hepatic impairment). No dose adjustment for Child-Pugh Class A or B; use with caution.
Child-Pugh A: no adjustment; Child-Pugh B: not recommended; Child-Pugh C: contraindicated.
Not indicated for pediatric use; safety and efficacy not established.
Safety and efficacy not established; no specific dosing guidelines.
No specific dose adjustment required; pharmacokinetics similar to younger adults. Monitor for vulvovaginal atrophy and thromboembolic risks.
No specific dose adjustment; monitor for dysphagia and esophageal adverse effects.
There is an increased risk of endometrial cancer in women with an intact uterus. Use only when necessary and consider periodic endometrial evaluation.
Increased risk of venous thromboembolic events (including deep vein thrombosis and pulmonary embolism) and death due to stroke. Use is contraindicated in women with active or past history of venous thromboembolism.
Endometrial cancer risk,Cardiovascular and cerebrovascular events (not evaluated in long-term studies),Venous thromboembolism (potential risk),Breast cancer (long-term safety not established),Use with caution in patients with hepatic impairment
Increased risk of venous thromboembolic events and stroke; consider risk-benefit in women at risk for these events. May cause hot flashes and leg cramps. Use with caution in patients with hepatic impairment or history of cholestasis. Not recommended for use in premenopausal women. Discontinue if prolonged immobilization occurs. Monitor lipid profile; may cause small reductions in HDL cholesterol.
Undiagnosed abnormal genital bleeding,Known or suspected estrogen-sensitive cancer (e.g., breast cancer),Active or history of venous thromboembolism (e.g., deep vein thrombosis, pulmonary embolism),Pregnancy or women who may become pregnant
Active or past history of venous thromboembolism (DVT, PE, retinal vein thrombosis), pregnancy (can cause fetal harm), women who are or may become pregnant, nursing mothers, patients with hypersensitivity to raloxifene or any component of the formulation.
Take with food to minimize GI side effects. No specific food restrictions; however, avoid grapefruit juice as it may increase drug levels via CYP3A4 inhibition.
No specific food interactions; take with food to minimize gastrointestinal side effects.
Ospemifene is contraindicated in pregnancy due to potential fetal harm. In animal studies, it caused fetal malformations (e.g., skeletal abnormalities) and embryo-fetal loss. There are no adequate human data; however, based on its estrogenic and antiestrogenic activity, it may interfere with fetal development. Use is not recommended at any trimester.
Ospemifene is contraindicated in pregnancy. Based on its mechanism as a selective estrogen receptor modulator (SERM) and animal studies showing embryotoxicity and teratogenicity, there is potential for fetal harm. First trimester exposure may increase risk of congenital anomalies; second/third trimester exposure may cause urogenital tract abnormalities and endocrine disruption.
It is unknown whether ospemifene is excreted in human breast milk. No M/P ratio is available. Due to potential serious adverse effects in the nursing infant, breastfeeding is not recommended during treatment and for one week after the last dose.
No data on human milk excretion. Ospemifene may suppress lactation due to estrogenic effects. M/P ratio unknown. Avoid breastfeeding during treatment and for at least 2 weeks after last dose.
Ospemifene is contraindicated in pregnancy; therefore, no dosing adjustments are recommended. If pregnancy occurs, therapy should be discontinued. Due to lack of data and potential harm, no alternative dosing during pregnancy is advised.
No dose adjustments studied; contraindicated in pregnancy. Pharmacokinetic changes (e.g., increased volume of distribution, altered clearance) may occur but no data to guide dosing.
Ospemifene is a selective estrogen receptor modulator (SERM) indicated for moderate to severe dyspareunia due to vulvar and vaginal atrophy (VVA) in postmenopausal women. It has estrogenic effects on vaginal tissue but antiestrogenic effects on breast and endometrium. Monitor for thromboembolic events; contraindicated in history of VTE or PE. Not for use in women with breast cancer or estrogen-dependent neoplasia. May cause hot flashes and vaginal discharge.
Ospemifene is a selective estrogen receptor modulator (SERM) indicated for moderate to severe dyspareunia due to vulvar and vaginal atrophy in postmenopausal women. Avoid in women with estrogen-dependent neoplasia, unexplained genital bleeding, or prior thromboembolic events. Monitor for endometrial hyperplasia because uterine stimulation can occur. Not for use in premenopausal women.
Take one 60 mg tablet daily with food to reduce gastrointestinal upset.,Notify your healthcare provider if you experience unusual vaginal bleeding, breast pain, or lumps.,Seek immediate medical attention for signs of blood clots: chest pain, shortness of breath, leg swelling or pain, sudden severe headache.,Do not use if you have a history of blood clots, breast cancer, or liver disease.,Ospemifene is for non-surgical women postmenopausal; it does not prevent pregnancy or sexually transmitted infections.,Avoid smoking and limit alcohol intake to reduce the risk of blood clots.
Take daily with food to reduce nausea.,Do not take if you have a history of blood clots, breast cancer, or uterine cancer.,Report any unusual vaginal bleeding, breast pain, or leg swelling immediately.,May cause hot flashes, vaginal discharge, or muscle spasms.,Use proper lubricants during intercourse; this medicine does not protect against STIs.,Continue regular pelvic exams and mammograms as recommended.
"Ospemifene, a selective estrogen receptor modulator, inhibits the metabolism of thiotepa, an alkylating agent, by competitively inhibiting cytochrome P450 (CYP) 2B6 and potentially other CYP enzymes involved in thiotepa's biotransformation. This leads to increased systemic exposure to thiotepa, elevating the risk of dose-dependent toxicities such as severe myelosuppression (e.g., neutropenia, thrombocytopenia) and mucositis. Clinically, coadministration may require significant thiotepa dose reduction to avoid excessive bone marrow suppression."
"Ospemifene is primarily metabolized by CYP3A4, and thioridazine is a moderate inhibitor of CYP3A4. Coadministration reduces ospemifene clearance, leading to elevated ospemifene serum concentrations, which may increase the risk of dose-dependent adverse effects such as thromboembolic events, hot flashes, and vaginal discharge. This interaction is clinically significant as it may exacerbate the endocrine and cardiovascular side effects of ospemifene."
"Ospemifene, a selective estrogen receptor modulator (SERM), is primarily metabolized by the cytochrome P450 enzyme CYP3A4. Clarithromycin is a potent macrolide antibiotic and a strong inhibitor of CYP3A4. Coadministration of clarithromycin with ospemifene significantly reduces the metabolic clearance of clarithromycin, leading to increased plasma concentrations of clarithromycin. This elevation can potentiate clarithromycin's adverse effects, including QT interval prolongation, cardiac arrhythmias, hepatotoxicity, and gastrointestinal disturbances, particularly in patients with preexisting risk factors."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about OSPEMIFENE vs OSPHENA, answered by our medical review team.
OSPEMIFENE is a Selective Estrogen Receptor Modulator (SERM) that works by Ospemifene is a selective estrogen receptor modulator (SERM) that acts as an agonist on estrogen receptors in vaginal tissues, leading to proliferation and maturation of vaginal epithelium, while exhibiting antagonist activity on breast and endometrial tissues.. OSPHENA is a Selective Estrogen Receptor Modulator (SERM) that works by Selective estrogen receptor modulator (SERM) that acts as an estrogen agonist on bone and lipid metabolism, and as an estrogen antagonist on breast and uterine tissue. It mimics estrogen's effects on bone by reducing bone resorption and increasing bone mineral density.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between OSPEMIFENE and OSPHENA depend on the specific clinical indication. These are both Selective Estrogen Receptor Modulator (SERM) agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of OSPEMIFENE is: 60 mg orally once daily.. The standard adult dose of OSPHENA is: 60 mg orally once daily with food.. 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 OSPEMIFENE and OSPHENA 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. OSPEMIFENE is classified as Category C. Ospemifene is contraindicated in pregnancy due to potential fetal harm. In animal studies, it caused fetal malformations (e.g., skeletal abnormalities) and embryo-fetal loss. There. OSPHENA is classified as Category C. Ospemifene is contraindicated in pregnancy. Based on its mechanism as a selective estrogen receptor modulator (SERM) and animal studies showing embryotoxicity and teratogenicity, t. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.