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Estramustine Phosphate Sodium
Class: Nitrogen mustard
- Capsules for oral use 140 mg estramustine phosphate.
Estramustine appears to act as a relatively weak alkylating agent and imparts a weak estrogenic activity. The estrogenic portion of the molecule acts as a carrier to facilitate selective uptake of the drug into estrogen receptor-positive cells. Because of the selective steroidal uptake, the alkylating effect of the nitrogen mustard is enhanced in these cells. Estramustine phosphate is readily dephosphorylated during absorption, and the major metabolites in plasma are estramustine, the estrone analog, estradiol, and estrone. Terminal half-life of estramustine phosphate is approximately 20 h and mainly excreted in the stool.
Readily dephosphorylated during absorption; major metabolites in plasma are estramustine, the estrone analog, estradiol, and estrone.
The t 1/2 is approximately 20 h. Majority excreted in the feces.
Special PopulationsHepatic Function Impairment
May be poorly metabolized in these patients.
Indications and Usage
Palliative therapy of metastatic or progressive prostate cancer.
Metastatic renal cell carcinoma.
Hypersensitivity to estradiol or nitrogen mustard; active thrombophlebitis or thromboembolic disorders, except where the actual tumor mass is the cause of the thromboembolic phenomenon and the benefits of therapy outweigh the risks.
Dosage and AdministrationProstate Cancer
PO 14 mg/kg/day (range, 10 to 16 mg/kg/day) in 3 to 4 divided doses for 30 to 90 days before assessing for continuation of therapy. Continue therapy as long as response is favorable.
Administer PO with water 1 h or more before or 2 h after meals.
Refrigerate. Capsules may be stored at room temperature for 24 to 48 h without affecting potency. Protect from light.
Milk, milk products, and calcium-rich foods or antacids may impair the absorption of estramustine.
Laboratory Test Interactions
Abnormalities of hepatic enzymes and of bilirubin have occurred but have seldom required cessation of therapy. Perform such tests at appropriate intervals during therapy and repeat after the drug has been withdrawn for 2 mo.
Hypertension; CHF; edema; increased risk of cerebrovascular accident; MI, thrombosis.
Lethargy; emotional lability; insomnia.
Rash; pruritus; dry skin; easy bruising.
Decreased glucose tolerance; breast tenderness or enlargement.
Nausea; vomiting; diarrhea; anorexia; flatulence; elevated LFTs.
Decreased glucose tolerance; gonadal suppression; breast tenderness; breast enlargement.
Leukopenia and thrombocytopenia have been reported in a small number of patients.
Safety and efficacy not established.
Estramustine may be poorly metabolized in patients with impaired liver function.
Both estradiol and nitrogen mustard are mutagenic. Advise use of contraceptive measures.
The risk of thrombosis including nonfatal MI, increases in men receiving estrogens for prostate cancer. Use with caution in patients with a history of thrombophlebitis, thrombosis, or thromboembolic disorders, especially if associated with estrogen therapy. Use with caution in patients with cerebral vascular or coronary artery disease.
Tolerance to glucose may be decreased. Monitor blood sugar in diabetic patient when therapy is started. Report significant changes to health care provider.
BP elevation may occur. Monitor BP periodically while on estramustine.
Exacerbation of preexisting or incipient peripheral edema or CHD may occur.
Calcium/phosphorus metabolism may be influenced. Use with caution in patients with metabolic bone disease associated with hypercalcemia or in patients with renal function impairment.
- Use contraceptive measures during therapy because of the possibility of mutagenic effects.
- Milk, milk products, and calcium-rich foods or antacids may impair the absorption of estramustine.
- Take with water at least 1 h before or 2 h after meals.
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