Estrogel (Estradiol Topical) - Drug Interactions, Contraindications, Overdosage

DRUG INTERACTIONS

D. Drug and Laboratory Test Interactions

1. Accelerated prothrombin time, partial thromboplastin time, and platelet aggregation time; increased platelet count; increased factors II, VII antigen, VIII antigen, VIII coagulant activity, IX, X, XII, VII-X complex, II-VII-X complex, and beta-thromboglobulin; decreased levels of anti-factor Xa and antithrombin III, decreased antithrombin III activity; increased levels of fibrinogen and fibrinogen activity; increased plasminogen antigen and activity.
2. Increased thyroid-binding globulin (TBG) leading to increased circulating total thyroid hormone levels, as measured by protein-bound iodine (PBI), T₄ levels (by column or by radioimmunoassay) or T₃ levels by radioimmunoassay. T₃ resin uptake is decreased, reflecting the elevated TBG. Free T₄ and T₃ concentrations are unaltered. Patients on thyroid-replacement therapy may require higher doses of thyroid hormone.
3. Other binding proteins may be elevated in serum (ie, corticosteroid-binding globulin, sex hormone-binding globulin, leading to increased total circulating corticosteroids and sex steroids, respectively). Free hormone concentrations may be decreased. Other plasma proteins may be increased (angiotensinogen/renin substrate, alpha-1-antitrypsin, ceruloplasmin).
4. Increased plasma HDL and HDL₂ cholesterol subfraction concentrations, reduced LDL cholesterol concentration, increased triglyceride levels.
5. Impaired glucose tolerance.
6. Reduced response to metyrapone test.

OVERDOSAGE

Serious adverse events have not been reported following acute ingestion of large doses of estrogen-containing products by young children. Overdosage of estrogen may cause nausea and vomiting, and withdrawal bleeding may occur in females.

CONTRAINDICATIONS

Estrogens should not be used in individuals with any of the following conditions:

1. Undiagnosed abnormal genital bleeding

2. Known, suspected, or history of breast cancer

3. Known or suspected estrogen-dependent neoplasia

4. Active deep vein thrombosis, pulmonary embolism, or history of these conditions

5. Active or recent (eg, within the past year) arterial thromboembolic disease (eg, stroke, myocardial infarction)

6. Liver dysfunction or disease

7. Known hypersensitivity to ingredients in EstroGel

8. Known or suspected pregnancy. There is no indication for EstroGel in pregnancy. There appears to be little or no increased risk of birth defects in children born to women who have used estrogens and progestins from oral contraceptives inadvertently during early pregnancy. (See PRECAUTIONS.)