(Commercial Product)
Available Dosage Strengths
20 mg
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Tamoxifen Citrate Tablets1,2,3
Tamoxifen, an oral selective estrogen receptor modulator (SERM) approved in the 1970s, has both estrogenic and antiestrogenic effects in the body. The drug is a competitor inhibitor of estrogen at the estrogen receptor in breast tissue. By inhibiting estrogen activity at the breast tissue estrogen receptor, it can decrease the growth of estrogen dependent breast tumors.
In females, tamoxifen is used for 1) the adjuvant treatment of breast cancer and for the treatment of metastatic breast cancer, 2) to reduce the risk of invasive breast cancer in women with ductal carcinoma in situ (DCIS) after surgery and radiation, and 3) to reduce the risk of breast cancer in women at high risk for breast cancer.
In males, tamoxifen’s activity as a SERM is used to increase testosterone in comparison to estrogen in hypogonadism to facilitate testosterone production in the testes.
Mechanism of Action3
In females, tamoxifen decreases estrogen binding to estrogen-dependent breast tissue. This activity of tamoxifen decreases the growth of estrogen-dependent breast tumors and on a molecular level, the inhibition of the expression of estrogen-dependent genes (RNA transcription). Tamoxifen’s activity results in reduced DNA polymerase activity, impaired thymidine utilization, blockade of estradiol uptake, and decreased estrogen response. Tamoxifen’s activity is cytostatic and occurs in the G2 phase. Tamoxifen also inhibits other factors involved in cancer growth, including insulin-like growth factor type 1 (IGF-1) and transforming growth factor-beta (TGF-beta).1,2 In males, tamoxifen works as an estrogen antagonist in the hypothalamus and pituitary gland to inhibit negative feedback from estrogen. This negative feedback allows for release of LH and FSH which results in the production of testosterone and spermatogenesis.
Common1,2
Contraindications1,2
Precautions1,2
Wells Pharmacy Network is a 503B-registered outsourcing facility that compounds sterile medications in accordance with current good manufacturing practices (cGMP). Certain FDA-approved products referenced on this site are distributed separately from compounded preparations and are not manufactured by Wells Pharmacy Network. Actual products in stock at time of dispensing may vary due to supply chain variability.
This information may not cover all possible drug information about this product. Call your doctor for medical advice and/or about side effects. You may report side effects to the FDA at 1-800-FDA-1088. A Wells Pharmacy Network pharmacist will be happy to answer any questions. For consultation, please call 1-800-622-4510.
