EMCYT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for EMCYT (EMCYT).
Estramustine is a combination of estradiol and nitrogen mustard. The estradiol moiety targets the drug to cells expressing estrogen receptors, while the nitrogen mustard alkylates DNA, inhibiting cell division primarily in prostate cancer cells.
| Metabolism | Metabolized in the liver via esterases and oxidative pathways; undergoes extensive first-pass metabolism. Active metabolite: estromustine. |
| Excretion | Renal: primarily as estramustine phosphate, estromustine, and estradiol; <1% as unchanged drug; fecal: ~15% |
| Half-life | Terminal half-life of estramustine phosphate: ~20 hours; estromustine: ~14 hours; clinical context: supports daily dosing with accumulation over 5-7 days |
| Protein binding | Estramustine phosphate: >90% bound to albumin and sex hormone-binding globulin (SHBG); estromustine: similarly bound |
| Volume of Distribution | Estramustine: approximately 3.5 L/kg, indicating extensive tissue distribution; clinical meaning: significant extravascular uptake, particularly in prostate tissue |
| Bioavailability | Oral: approximately 75% absorbed, but first-pass metabolism reduces systemic availability of parent compound; active metabolites (estromustine, estradiol) have higher bioavailability; food may reduce absorption |
| Onset of Action | Oral: clinical effect (e.g., prostate-specific antigen decline) within 2-4 weeks; IV: not applicable as oral only |
| Duration of Action | Duration: persists for 2-3 weeks after discontinuation due to active metabolites and prolonged half-life; clinical note: requires continuous dosing for sustained effect |
| Molecular Weight | 440.4 |
Estramustine phosphate sodium: 14 mg/kg/day orally in 3-4 divided doses, typically 140 mg four times daily. Administer on an empty stomach (1 hour before or 2 hours after meals).
| Dosage form | CAPSULE |
| Renal impairment | GFR 30-50 mL/min: reduce dose by 50%. GFR <30 mL/min: contraindicated. Not dialyzable. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50%. Child-Pugh C: avoid use. |
| Pediatric use | Not established; safety and efficacy in pediatric patients have not been studied. |
| Geriatric use | No specific dose adjustment; however, monitor for increased risk of thromboembolic events, fluid retention, and cardiovascular toxicity. Start at lower end of dosing range. |
| 1st trimester | Contraindicated due to teratogenic risk (androgen-like effects causing virilization of female fetuses). |
| 2nd trimester | Contraindicated due to risk of fetal harm, including ambiguous genitalia in female fetuses. |
| 3rd trimester | Contraindicated due to potential adverse effects on fetal development. |
Clinical note
Comprehensive clinical and safety monograph for EMCYT (EMCYT).
| Placental transfer | Estradiol metabolites cross placenta; estramustine phosphate likely crosses due to low molecular weight. |
| Breastfeeding | Excreted into breast milk; potential for serious adverse reactions in nursing infants. Discontinue nursing or discontinue drug, taking into account importance of drug to mother. |
| Lactation Rating |
■ FDA Black Box Warning
None.
| Serious Effects |
Active thrombophlebitisThromboembolic disordersHistory of thromboembolic eventsPregnancyLactationSevere hepatic impairment
| Precautions | Cardiovascular risk: increased incidence of thromboembolic events, myocardial infarction, and stroke, especially with prior cardiovascular disease., Sodium and fluid retention may exacerbate hypertension, congestive heart failure, or epilepsy., Glucose intolerance may occur; monitor blood glucose in diabetic patients., Hepatic impairment: use with caution; monitor liver function., Osteoporosis risk with long-term use due to estrogenic effects., Gynecomastia, breast tenderness, and other estrogenic effects are common. |
| Food/Dietary | Avoid dairy products, calcium-fortified foods, and calcium supplements for at least 1 hour before and 2 hours after taking estramustine. Calcium binds to estramustine, significantly reducing absorption. Also avoid high-fat meals as they may increase absorption variability. Grapefruit may affect metabolism; caution advised. |
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| L5 (Contraindicated) |
| Teratogenic Risk | Pregnancy Category X. Estramustine phosphate is contraindicated in pregnancy due to its cytotoxic and hormonal effects. First trimester: high risk of severe fetal malformations including genitourinary tract abnormalities, cardiac defects, and neural tube defects. Second and third trimesters: risk of fetal growth restriction, oligohydramnios, and neonatal myelosuppression. Adequate contraception is mandatory in women of childbearing potential. |
| Fetal Monitoring | Monitor maternal complete blood count (CBC) with differential, hepatic function tests (AST, ALT, bilirubin), renal function (serum creatinine, BUN), and uric acid levels every 2 weeks during therapy. Fetal monitoring: serial ultrasound for growth restriction and amniotic fluid volume; fetal echocardiography if first-trimester exposure. Monitor newborn for myelosuppression, electrolyte disturbances, and liver dysfunction. |
| Fertility Effects | Estramustine phosphate can impair fertility. In males: inhibits spermatogenesis, potentially causing oligospermia or azoospermia; may be irreversible. In females: disruption of menstrual cycle, anovulation, and premature ovarian failure. Advise counseling on fertility preservation prior to therapy. |
| Clinical Pearls | Estramustine phosphate (Emcyt) is an antineoplastic agent combining estradiol and mechlorethamine. It is used primarily in hormone-refractory prostate cancer. Cardiac risk: estramustine can increase cardiovascular events, especially in men with preexisting heart disease. Thrombosis risk: monitor for thromboembolic events; consider prophylactic anticoagulation. Calcium-containing foods or supplements can reduce absorption by chelation; avoid concurrent intake. Administer on an empty stomach: at least 1 hour before or 2 hours after meals. Adverse effects: gynecomastia, nausea, edema, and potential for hepatotoxicity. Monitor LFTs and cardiac function regularly. |
| Patient Advice | Take estramustine on an empty stomach (1 hour before or 2 hours after meals) with a full glass of water. · Avoid calcium-rich foods (e.g., dairy products, calcium-fortified juices) and calcium supplements around the time of dosing. · Do not crush or chew capsules; swallow them whole. · Report any signs of blood clots (leg pain, swelling, shortness of breath, chest pain) or heart problems (chest discomfort, palpitations) immediately. · Expect possible nausea, breast tenderness or enlargement, and fluid retention; discuss management with your doctor. · Keep capsules in the refrigerator, protected from light, and out of reach of children. · Do not stop taking this medication without consulting your healthcare provider. |