tamoxifen, Nolvadex

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GENERIC NAME: tamoxifen

BRAND NAME: Nolvadex (Discontinued)

DRUG CLASS AND MECHANISM: Tamoxifen is an anti-estrogen that prevents the effects of estrogens on tissues. The precise mechanism of its action is unknown, but one possibility is that it binds and blocks estrogen receptors on the surface of cells, preventing estrogens from binding and activating the cell. It is used in patients for treating and preventing breast cancer. Tamoxifen was approved by the FDA in December 1997.



PREPARATIONS: Tablets: 10 and 20 mg. Solution: 10 mg/5 ml

STORAGE: Tamoxifen should be stored in a dry place at 15-30 C (59-86 F).

PRESCRIBED FOR: Tamoxifen is used for the treatment of invasive breast cancer in men and women, the most common type of breast cancer, following surgery and/or radiation and for preventing invasive breast cancer in women at high risk for developing it. Tamoxifen also is used for the treatment of women following surgery and radiation for a less common type of breast cancer called ductal carcinoma in situ (DCIS or intraductal carcinoma). Women who have had DCIS are at high risk for developing invasive breast cancer at a later date, and tamoxifen prevents development of the invasive cancer in almost half of the women during the first five years of treatment. Occasionally, tamoxifen is used to stimulate ovulation.

DOSING: The dose for metastatic breast cancer treatment, DCIS, and prevention of breast cancer is 10 mg twice daily or 20 mg once daily for 5 years. The dose for stimulation of ovulation is 5-40 mg twice daily for 4 days. Tamoxifen can be taken with food.

DRUG INTERACTIONS: Tamoxifen increases the blood thinning effect of warfarin (Coumadin) and reduces blood levels of letrozole (Femara) and anastrozole (Arimidex). Phenobarbitol and rifampin may reduce blood levels of tamoxifen by increasing the breadkdown of tamoxifen.

PREGNANCY: Tamoxifen should not be used during pregnancy because it can harm the fetus.

NURSING MOTHERS: It is not known whether tamoxifen is excreted in breast milk. Tamoxifen causes a reduction in milk production. Women taking tamoxifen should not breastfeed.

SIDE EFFECTS: The most common side effects associated of tamoxifen are hot flashes, weight gain, abnormal or absence of menstrual periods, vaginal discharge, and nausea. Cough, fatigue, fluid retention, bone pain, cataracts, and depression also occur. Tamoxifen is associated with blood clots leading to deep vein thrombosis and pulmonary embolism. Tamoxifen can cause abnormalities of liver tests, reduced white blood cells, red blood cells, and platelets. Reduced platelets can lead to bleeding. Patients should keep appointments for blood work to monitor for these side effects. Patients should report any suspected side effects immediately, especially bleeding and yellowing of the skin.

Reference: FDA Prescribing Information

Last Editorial Review: 3/2/2012

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