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 |
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 | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for EMCYT (EMCYT).
| Breastfeeding | No data on excretion into breast milk. Due to potential for serious adverse reactions in nursing infants (e.g., hormonal disruption, myelosuppression), breastfeeding is contraindicated during therapy and for at least 1 month after last dose. M/P ratio not determined. |
| 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. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to estramustine or estradiol/nitrogen mustard","Active thrombophlebitis or thromboembolic disorders (e.g., deep vein thrombosis, pulmonary embolism)","Severe 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."] |
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| 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. |