PEBC: What You Need to Know: Tamoxifen
Updated: Jul 25, 2020
adjuvant for breast cancer treatment
Tamoxifen is a prodrug which is converted to the active metabolite endoxifen via CYP 2D6 metabolism. Endoxifen blocks the receptor site for estrogen to exert its effects on breast cancer tissue.
20 mg once daily for 10 years (extended treatment) *use in premenopausal patients (if post menopausal, use aromatase inhibitors)
Adverse Effects: LOTS!
-hot flashes (related to anti-estrogen mechanism)
-increased risk of clots (stroke, deep vein thrombosis, pulmonary embolism)
-increased risk of endometrial cancer
-bone and muscle pain
-altered lipid profile
CYP 2D6 inhibitors (terbinafine, fluoxetine, paroxetine, bupropion): reduced tamoxifen activation --> failure of tamoxifen