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Estramustine (Emcyt®)
What malignancy is estramustine approved for?
• Progressive or metastatic prostate cancer
How does estramustine work?
• Estramustine is a carbamate-linked conjugate of nor-nitrogen mustard (an alkylating agent) and estradiol
• It was synthesized on the premise that the estradiol component would bind to the estrogen receptor in breast cancer cells and selectively deliver the alkylating agent, nor-nitrogen mustard; however, it was neither found to have clinical activity in breast cancer, nor did it demonstrate alkylating agent activity
• Estramustine instead accumulates in the prostate by binding to a prostate-specific protein and inhibits microtubule function in prostate cancer cells
• Estramustine is cell cycle specific to the G2/M phase
What is the usual dose of estramustine?
• 14 mg/kg/day orally in 3 to 4 divided doses
Is estramustine metabolized/eliminated renally or hepatically?
• Estramustine is eliminated hepatically
Are there drug interactions with estramustine?
• Absorption of estramustine can be significantly decreased by coadministration with calcium (including antacids) and calcium-rich foods; patients should take estramustine on an empty stomach, at least 1 hour before or 2 hours after eating.
What are the most common adverse effects of estramustine?
• Nausea, vomiting, and diarrhea
• Gynecomastia, breast tenderness, decreased libido
• Fluid retention
• Increased liver enzymes
• Thromboembolism, congestive heart failure (CHF), myocardial infarction (MI) (rare, but serious)
What is the emetogenicity level of estramustine?
• Estramustine is categorized as moderate to high emetogenic risk