Tamoxifen

DEA Class; Rx

Common Brand Names; Soltamox

Indicated for the treatment of breast cancer.

Hypersensitivity

Pregnancy

Undiagnosed vaginal bleeding

Patients who require concomitant warfarin therapy or have a history of deep vein thrombosis or pulmonary embolus if indication for treatment is either reduction of breast cancer incidence in high-risk patients or risk reduction of invasive breast cancer after treatment of DCIS

Liver cancer and changes in liver enzyme levels reported with use; on rare occasions, a spectrum of more severe liver abnormalities including fatty liver, cholestasis, hepatitis and hepatic necrosis, that have included fatalities, also reported; monitor liver function periodically

Unknown whether an increased risk for other (non-uterine) cancers is associated with tamoxifen

Hypercalcemia reported in some breast cancer patients with bone metastases within a few weeks of starting treatment; if hypercalcemia occurs, treat as appropriate; if hypercalcemia is severe, discontinue therapy

CYP2D6 polymorphism-CYP2D6 converts tamoxifen to active metabolite endoxifen; lowered CYP2D6 activity or concomitant CYP2D6 inhibitors may reduce tamoxifen efficacy

Decreases in platelet counts, usually to 50,000-100,000/mm3, infrequently lower, reported in patients receiving therapy for breast cancer; hemorrhagic episodes have occurred, but not certain if episodes were due to tamoxifen therapy; leukopenia, sometimes in association with anemia and/or thrombocytopenia reported; neutropenia and pancytopenia also reported; perform periodic complete blood counts, including platelet counts

Ocular disturbances, including corneal changes, decrement in color vision perception, retinal vein thrombosis, and retinopathy reported; an increased incidence of cataracts and need for cataract surgery reported; patients should seek medical attention if they experience visual disturbance

Increased incidence of thromboembolic events (eg, deep vein thrombosis, pulmonary embolism), during tamoxifen therapy; when tamoxifen is coadministered with chemotherapy, there is further increase in risk of thromboembolic events; for treatment of breast cancer, carefully consider risks and benefits of tamoxifen in women with a history of thromboembolic events; advise patients to seek medical attention immediately if signs or symptoms of a thromboembolic event occur

Fetal harm may occur when administered to a pregnant woman

Tamoxifen reported to inhibit lactation