Emcyt

EMCYT- estramustine phosphate sodium capsule
Pharmacia and Upjohn Company LLC

DESCRIPTION

Estramustine phosphate sodium, an antineoplastic agent, is an off-white powder readily soluble in water. EMCYT Capsules are white and opaque, each containing estramustine phosphate sodium as the disodium salt monohydrate equivalent to 140 mg estramustine phosphate, for oral administration. Each capsule also contains magnesium stearate, silicon dioxide, sodium lauryl sulfate, and talc. Gelatin capsule shells contain the following pigment: titanium dioxide.

Chemically, estramustine phosphate sodium is estra-1,3,5(10)-triene-3,17-diol(17β)-,3-[bis(2-chloroethyl)carbamate] 17-(dihydrogen phosphate), disodium salt, monohydrate. It is also referred to as estradiol 3-[bis(2-chloroethyl)carbamate] 17-(dihydrogen phosphate), disodium salt, monohydrate. Estramustine phosphate sodium has an empiric formula of C23 H30 Cl2 NNa2 O6 P•H2 O, a calculated molecular weight of 582.4, and the following structural formula:

Chemical Structure
(click image for full-size original)

CLINICAL PHARMACOLOGY

Estramustine phosphate (Figure 1) is a molecule combining estradiol and nornitrogen mustard by a carbamate link. The molecule is phosphorylated to make it water soluble.

Chemical Structure
(click image for full-size original)

Estramustine phosphate taken orally is readily dephosphorylated during absorption, and the major metabolites in plasma are estramustine (Figure 2), the estrone analog (Figure 3), estradiol, and estrone.

Chemical StructureChemical Structure

Prolonged treatment with estramustine phosphate produces elevated total plasma concentrations of estradiol that fall within ranges similar to the elevated estradiol levels found in prostatic cancer patients given conventional estradiol therapy. Estrogenic effects, as demonstrated by changes in circulating levels of steroids and pituitary hormones, are similar in patients treated with either estramustine phosphate or conventional estradiol.

The metabolic urinary patterns of the estradiol moiety of estramustine phosphate and estradiol itself are very similar, although the metabolites derived from estramustine phosphate are excreted at a slower rate.

Emcyt Indications and Usage

EMCYT Capsules are indicated in the palliative treatment of patients with metastatic and/or progressive carcinoma of the prostate.

CONTRAINDICATIONS

EMCYT Capsules should not be used in patients with any of the following conditions:

1)
Known hypersensitivity to either estradiol or to nitrogen mustard.
2)
Active thrombophlebitis or thromboembolic disorders, except in those cases where the actual tumor mass is the cause of the thromboembolic phenomenon and the physician feels the benefits of therapy may outweigh the risks.

WARNINGS

It has been shown that there is an increased risk of thrombosis, including fatal and nonfatal myocardial infarction, in men receiving estrogens for prostatic cancer. EMCYT Capsules should be used with caution in patients with a history of thrombophlebitis, thrombosis, or thromboembolic disorders, especially if they were associated with estrogen therapy. Caution should also be used in patients with cerebral vascular or coronary artery disease.

Glucose Tolerance—Because glucose tolerance may be decreased, diabetic patients should be carefully observed while receiving EMCYT.

Elevated Blood Pressure—Because hypertension may occur, blood pressure should be monitored periodically.

PRECAUTIONS

General

Fluid Retention. Exacerbation of preexisting or incipient peripheral edema or congestive heart disease has been seen in some patients receiving therapy with EMCYT Capsules. Other conditions which might be influenced by fluid retention, such as epilepsy, migraine, or renal dysfunction, require careful observation.

EMCYT may be poorly metabolized in patients with impaired liver function and should be administered with caution in such patients.

Because EMCYT may influence the metabolism of calcium and phosphorus, it should be used with caution in patients with metabolic bone diseases that are associated with hypercalcemia or in patients with renal insufficiency. Patients with prostate cancer and osteoblastic metastases are at risk for hypocalcemia and should have calcium levels closely monitored.

Gynecomastia and impotence are known estrogenic effects.

Allergic reactions and angioedema at times involving the airway have been reported.

Information for the Patient

Because of the possibility of mutagenic effects, patients should be advised to use contraceptive measures.

Laboratory Tests

Certain endocrine and liver function tests may be affected by estrogen-containing drugs. EMCYT may depress testosterone levels. Abnormalities of hepatic enzymes and of bilirubin have occurred in patients receiving EMCYT. Such tests should be done at appropriate intervals during therapy and repeated after the drug has been withdrawn for two months.

Food/Drug Interaction

Milk, milk products, and calcium-rich foods or drugs may impair the absorption of EMCYT.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Long-term continuous administration of estrogens in certain animal species increases the frequency of carcinomas of the breast and liver. Compounds structurally similar to EMCYT are carcinogenic in mice. Carcinogenic studies of EMCYT have not been conducted in man. Although testing by the Ames method failed to demonstrate mutagenicity for estramustine phosphate sodium, it is known that both estradiol and nitrogen mustard are mutagenic. For this reason and because some patients who had been impotent while on estrogen therapy have regained potency while taking EMCYT, the patient should be advised to use contraceptive measures.

Adverse Reactions to Emcyt

In a randomized, double-blind trial comparing therapy with EMCYT Capsules in 93 patients (11.5 to 15.9 mg/kg/day) or diethylstilbestrol (DES) in 93 patients (3.0 mg/day), the following adverse effects were reported:

EMCYT
n=93
DES
n=93
CARDIOVASCULAR-RESPIRATORY
Cardiac Arrest 0 2
Cerebrovascular Accident 2 0
Myocardial Infarction 3 1
Thrombophlebitis 3 7
Pulmonary Emboli 2 5
Congestive Heart Failure 3 2
Edema 19 17
Dyspnea 11 3
Leg Cramps 8 11
Upper Respiratory Discharge 1 1
Hoarseness 1 0
GASTROINTESTINAL
Nausea 15 8
Diarrhea 12 11
Minor Gastrointestinal Upset 11 6
Anorexia 4 3
Flatulence 2 0
Vomiting 1 1
Gastrointestinal Bleeding 1 0
Burning Throat 1 0
Thirst 1 0
INTEGUMENTARY
Rash 1 4
Pruritus 2 2
Dry Skin 2 0
Pigment Changes 0 3
Easy Bruising 3 0
Flushing 1 0
Night Sweats 0 1
Fingertip—Peeling Skin 1 0
Thinning Hair 1 1
BREAST CHANGES
Tenderness 66 64
Enlargement
Mild 60 54
Moderate 10 16
Marked 0 5
MISCELLANEOUS
Lethargy Alone 4 3
Depression 0 2
Emotional Lability 2 0
Insomnia 3 0
Headache 1 1
Anxiety 1 0
Chest Pain 1 1
Hot Flashes 0 1
Pain in Eyes 0 1
Tearing of Eyes 1 1
Tinnitus 0 1
LABORATORY ABNORMALITIES
Hematologic
Leukopenia 4 2
Thrombopenia 1 2
Hepatic
Bilirubin Alone 1 5
Bilirubin and LDH 0 1
Bilirubin and SGOT 2 1
Bilirubin, LDH and SGOT 2 0
LDH and/or SGOT 31 28
Miscellaneous
Hypercalcemia—Transient 0 1
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