Raloxifene Traditionally hormone replacement therapy with estrogen was being used to prevent/treat osteoporosis in postmenopausal worsen. H has been shown to reduce the risk of osteoporosis in women. But long term use of estrogen leads to range of adverse effect including cardiovascular disease, stroke, pulmonary emboli and invasive breast cancer. These serious adverse effect made to look for other options. Selective estrogen receptor modulators These are class of compounds that act on estrogen receptors. Their characteristic feature is that they do not have pure agonist or antagonistic action on estrogen receptors. - Their selective action distinguishes these substances .from pure receptor agonist or antagonist. - SERMS are "selective" that means SERMS block estrogen in some tissues and activate estrogen action in others. - All the SERMS bind to the estrogen receptor but each agent produces a unique receptor drug conformation. - As a result specific coactivator or co-oppressor proteins are bound to the receptor resulting in differential effects. Two SERMS are currently being used Raloxifens For the t/t and prevention of osteoporosis Tamoxifen --> For the t/t and prevention of Breast Ca The .first SERM to reach the market was Tamoxifen which blocks the stimulative effect of estrogen on breast tissue and is used in breast cancer. Raloxifene is the second SERM to be approved by the FDA. Raloxifens has been approved for the tit and prevention of osteoporosis in postmenopausal women. Raloxifens acts like estrogen on bone and helps to build and maintain bone density. - Raloxifen has been shown in clinical trials to increase bone density in the spine and hip and to reduce the risk of spinal fractures in women with osteoporosis. While it acts like estrogen on bone, it blocks the action of estrogen on breast and uterus. - This profile makes it very useful for the t/t of osteoporosis because Raloxifene provides the bone benefits of estrogen without increasing the risk for estrogen related breast and uterine cancers. Raloxifene in Breast cancer Due to its antiestrogenic effect on breast, Raloxifene has been shown to reduce the risk of invasive breast cancer in women who are taking it for osteoporosis. Raloxifene reduces the risk of breast cancer by 50-70% in both low risk and high risk postmenopausal women. The national cancer institute U.S.A. funded the STUDY OF TAMOXIFEN AND RALOXIFEN (STAR) a clinical trial comparing raloxtfens with tamoxifen in preventing breast cancer, in postmenopausal women who are at increased risk of developing the disease. The study found that tamoxifen and Raloxifen are equally effective in reducing invasive breast cancer risk in postmenopausal women who are at increased risk of the disease. The study also .found out that women who took raloxifen had fewer uterine cancer and.fewer blood clots than women who took tamoxifen. However, Raloxifen did not decrease the risk of noninvasive breast Ca. On September 14 2007, the US. food and drug administration announced approval of raloxifens for reducing the risk of invasive breast cancer in postmenopausal women with osteoporosis and in postmenopausal women at high risk for invasive cancer.