ESTRADIOL VALERATE
Clinical safety rating: avoid
Inducers of CYP450 enzymes (eg carbamazepine) may decrease estrogen levels Increases risk of thromboembolic disorders and endometrial cancer.
Estradiol valerate is a prodrug of estradiol, a natural estrogen. Estrogens exert their effects by binding to estrogen receptors (ERα and ERβ), which act as transcription factors regulating gene expression. This leads to proliferation and growth of reproductive tissues, modulation of gonadotropin secretion, and effects on bone density, lipid metabolism, and other tissues.
| Metabolism | Estradiol valerate is rapidly hydrolyzed to estradiol after injection. Estradiol is extensively metabolized in the liver via oxidation (CYP1A2, CYP3A4, CYP1B1, CYP2C9, CYP2C19) and conjugation (glucuronidation and sulfation). Major metabolites include estrone, estriol, and their conjugates. Enterohepatic recirculation occurs. |
| Excretion | Renal (approximately 50% as glucuronide and sulfate conjugates), biliary/fecal (approximately 30-40% as conjugates), with enterohepatic circulation. |
| Half-life | Terminal elimination half-life is approximately 12-14 hours after intramuscular administration, allowing for weekly or biweekly dosing intervals. |
| Protein binding | Approximately 96% bound to albumin and sex hormone-binding globulin (SHBG). |
| Volume of Distribution | Apparent volume of distribution is approximately 0.5 L/kg (range 0.4-0.6 L/kg), indicating distribution into total body water and some tissue binding. |
| Bioavailability | Intramuscular: 100% (complete bioavailability). Oral: estradiol valerate is not administered orally; oral estradiol has variable bioavailability (5-10%) due to first-pass metabolism. |
| Onset of Action | Intramuscular: clinical effects (e.g., estrogenic effects on vaginal epithelium) appear within 2-3 days; maximum serum concentrations occur 2-5 days post-injection. |
| Duration of Action | Intramuscular: duration of action is 2-4 weeks depending on dose; estradiol valerate is a prodrug with sustained release from the injection site. |
| Molecular Weight | 356.5 |
1-2 mg orally once daily adjusted based on response; for hormone therapy, 5-20 mg intramuscularly every 4 weeks.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment required; caution in severe impairment (GFR < 30 mL/min) due to potential fluid retention. |
| Liver impairment | Contraindicated in Child-Pugh class C; for Child-Pugh class A or B, reduce dose by 50% and monitor liver function. |
| Pediatric use | Not typically used; for induction of puberty, start 0.5 mg orally once daily, titrate every 3-6 months based on Tanner staging. |
| Geriatric use | Start at lowest effective dose; monitor for thromboembolism and cardiovascular events; consider transdermal route to reduce first-pass metabolism. |
| 1st trimester | Contraindicated; risk of fetal harm including congenital anomalies (e.g., cardiac defects, hypospadias) and potential for pregnancy loss. Use only if clearly needed and no alternative. |
| 2nd trimester | Not recommended; associated with fetal risks including potential for genital abnormalities in females. Use only if benefit outweighs risk. |
| 3rd trimester | Not recommended; may cause fetal harm including genital abnormalities in female fetuses, and potential for uterine hemorrhage. Avoid use during this period. |
Clinical note
Inducers of CYP450 enzymes (eg carbamazepine) may decrease estrogen levels Increases risk of thromboembolic disorders and endometrial cancer.
| FDA category | Positive |
| Placental transfer | Estradiol valerate crosses the placenta. Estradiol levels in fetal circulation are approximately 5-20% of maternal levels after administration. |
■ FDA Black Box Warning
Estrogens increase the risk of endometrial cancer in postmenopausal women. Progestin should be used in women with an intact uterus. Estrogens should not be used to prevent cardiovascular disease. The Women's Health Initiative (WHI) trials reported increased risks of stroke, deep vein thrombosis, pulmonary embolism, and myocardial infarction in postmenopausal women treated with oral conjugated estrogens plus medroxyprogesterone acetate. The risk of dementia was increased in postmenopausal women aged 65 years or older treated with oral conjugated estrogens plus medroxyprogesterone acetate.
| Common Effects | osteoporosis prevention |
| Serious Effects |
Known or suspected pregnancyUndiagnosed abnormal genital bleedingKnown or suspected estrogen-dependent neoplasia (e.g., breast cancer, endometrial cancer)Active thromboembolic disorders or history (e.g., deep vein thrombosis, pulmonary embolism, myocardial infarction)Known or suspected history of thrombophlebitisHypersensitivity to estradiol valerate or any component
| Precautions | Cardiovascular disorders: Increased risk of stroke, DVT, PE, and MI, Malignant neoplasms: Endometrial cancer, breast cancer (controversial), and ovarian cancer, Dementia: Increased risk in women aged 65 and older, Gallbladder disease: Increased risk, Hypercalcemia: In patients with breast cancer and bone metastases, Visual abnormalities: Retinal vascular thrombosis; discontinue if sudden vision loss or proptosis occurs, Hereditary angioedema: Estrogens can exacerbate symptoms, Pre-existing hypertriglyceridemia: Risk of pancreatitis |
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| Breastfeeding | Estradiol valerate is excreted in breast milk in small amounts. May reduce milk production and quality. Use during breastfeeding only if clearly indicated and monitor infant for signs of estrogen excess (e.g., breast tenderness, vaginal discharge). |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | First trimester: Estradiol valerate is contraindicated in pregnant women due to known teratogenic effects. Exposure during embryogenesis may cause congenital anomalies including cardiovascular and urogenital defects. Second and third trimesters: Continued fetal exposure may lead to feminization of male fetuses and other endocrine-disrupting effects. Dosage forms used in pregnancy are typically not indicated. |
| Fetal Monitoring | Inadvertent exposure during pregnancy: Monitor fetus for signs of congenital anomalies via high-resolution ultrasound and maternal serum screening. For ongoing use: Assess liver function, blood pressure, and glucose tolerance. Fetal monitoring includes growth parameters and amniotic fluid volume. |
| Fertility Effects | Estradiol valerate can suppress ovulation, potentially reducing fertility during use. Upon discontinuation, return to fertility is generally prompt. In assisted reproduction, it is used to synchronize cycles; no long-term negative impact on fertility. |
| Food/Dietary | Grapefruit and grapefruit juice may increase estradiol levels and risk of side effects (avoid). No other significant food interactions; but take with food to reduce gastrointestinal upset. |
| Clinical Pearls | Estradiol valerate is a prodrug of estradiol used in hormone replacement therapy (HRT) and contraception. Monitor for thromboembolic events, especially in smokers >35 years. Start with lowest effective dose. Avoid in patients with breast cancer, active liver disease, or unexplained vaginal bleeding. Can increase risk of endometrial cancer if used without progestin in women with intact uterus. |
| Patient Advice | Take exactly as prescribed; do not skip doses. · Report any signs of blood clots (leg pain, chest pain, sudden shortness of breath, vision changes) immediately. · Avoid smoking; increases risk of serious cardiovascular side effects. · This medication does not protect against HIV or other STDs. · May cause nausea, breast tenderness, or mood changes; these often improve with time. · Use effective non-hormonal contraception if needed; estradiol valerate is not for contraception unless combined with progestin. · Regular gynecologic exams and mammograms recommended during therapy. · If you have a uterus, you may need to take a progestin to reduce risk of endometrial cancer. |