Raloxifene Evista - Protecting Your Bones: Osteoporosis

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Raloxifene (Evista)

Raloxifene is one of a class of drugs known as selective estrogen receptor modulators (SERMs). SERMs such as tamoxifen and raloxifene, which are often called "designer estrogens," have generated a great deal of interest due to their ability to mimic some of estrogen's positive effects without some of the negative consequences (see "Hormone therapy"). Like estrogen, raloxifene slows bone loss, but it does not increase the risk for uterine cancer and it seems to protect against breast cancer.

SERMs work by traveling to target cells where they attach to estrogen receptors, in the way a key would fit a lock. If there is a good fit between a hormone and receptor, the connection stimulates a response in the cells — for example, encouraging the growth of endometrial tissue or certain kinds of cancerous tumors. But if the fit isn't precise, no activity is sparked. By bonding to a receptor without stimulating it, the SERMs essentially block out estrogen, keeping it from attaching to the receptor and triggering a reaction. In this manner, SERMs can inhibit tumor growth. SERMs also seem to lower the levels of LDL cholesterol (commonly referred to as "bad" cholesterol). Side effects are rare, but do include hot flashes and deep vein thrombosis, a condition causing blood clots in deep veins, most commonly in the legs.

Raloxifene, which is used to prevent or treat osteoporosis in women, slows bone loss and offers modest increases in bone density. In clinical studies, it has reduced spinal fractures by 30% to 50%.

It has other positive effects, too. In a study of 7,705 postmenopausal women who had osteoporosis, known as the Multiple Outcomes of Raloxifene Evaluation (MORE), raloxifene reduced the risk for breast cancer by 76%. The results were even more impressive for a particular type of cancer, estrogen receptor–positive breast cancer, which is the most common form of breast cancer among older women. Some doctors are beginning to prescribe raloxifene as a preventive medication for breast cancer.

Last updated:	January 23, 2007