Tamoxifen
Purpose of Medication and Method of Action
Tamoxifen is indicated as adjuvant therapy for the treament of axillary node negative breast cancer in women following mastectomy. It is also approved for use in node-positive disease and as an alternative to ovarian radiation or oopherectomy (removal of ovaries) in women with advanced disease. It acts by blocking the estrogen receptor on the tumor tissue and thus slows the growth of estrogen-receptor positive tumor.
Side Effects
These are usually mild and include flushing and/or hot flashes (25%-50%), vaginal discharge (30%), weight loss (22%), and nausea and vomiting (25%).
Drug Interactions
An interaction exists between tamoxifen and oral anticoagulants (warfarin, dicumerol) with an increase in anticoagulant effect when tamoxifen is added to existing anticoagulant therapy. Close monitoring of prothrombin time is necessary if the two drugs are given together.
Cautions and Contraindications
Visual disturbances have been reported and periodic eye examinations are recommended. Because of an increased incidence of endometrial cancer associated with tamoxifen, report any unusual vaginal bleeding to your physician.
Usual Dose
The usual dose is 10 mg two times a day. Although an increase to 40 mg/day has been approved, there does not appear to be any therapeutic value in the higher dose.
Patient Medication Information
These information sheets do not list all known side effects of the medications, only the most common side effects. For a complete list of side effects please contact your local pharmacy or the actual drug manufacturing company.