Selective Estrogen Receptor Modulators
Raloxifene (Evista) has the ability to bind to and activate the estrogen receptor while exhibiting tissue-specific effects distinct from estradiol.9 As a result, raloxifene is the first of a benzothiophene series of antiestrogens to be labeled a SERM. (Droloxifine, idoxifene and toremifene are similar SERM agents, but they are still considered experimental.) Raloxifene was specifically developed to maintain beneficial estrogenic activity on bone and lipids and antiestrogenic activity on endometrial and breast tissue. In December 1997, the U.S. Food and Drug Administration (FDA) labeled raloxifene for the prevention of osteoporosis.
Although the exact mechanism of action of raloxifene and other similar compounds has not yet been determined, it has been hypothesized that these agents work by inducing conformational changes in the estrogen receptor, resulting in differential expression of specific estrogen-regulated genes in different tissues.10 Activation of the estrogen receptor by these compounds may involve multiple molecular pathways that may result in gene expression of ligand-, tissue- and/or gene-specific receptors.11
Raloxifen (Evista) a different approach
Because SERMs are capable of inducing specific changes in the estrogen receptor, it is not surprising that they may mediate specific pharmacologic activity through their unique agonist or antagonist properties. For example, the agonistic properties of raloxifene on bone tissue were recently demonstrated by the specific activation of the human transforming growth factor-b3 gene, which is an important regulator of bone remodeling.12
Scientists discovered the link between raloxifene and breast cancer in a somewhat roundabout fashion. They were studying the drug's effectiveness in preventing and treating another disease — osteoporosis — when they discovered it could help in preventing breast cancer as well. In fact, the women enrolled in that three-year osteoporosis study experienced a 50 to 70 percent reduction in breast cancer rates compared to the general population. In addition, raloxifene — unlike tamoxifen — does not appear to increase the risk of endometrial cancer, nor does it appear to cause the eye problems (cataracts) associated with tamoxifen. The verdict is still out, however, on whether raloxifene — like tamoxifen — increases a person's risk for pulmonary embolism and deep-vein thrombosis. While some studies suggest it does, not all research supports this finding.
The less serious side effects associated with raloxifene are similar to those reported by women taking tamoxifen or undergoing hormone replacement therapy. In the case of raloxifene, the most common of these are hot flashes and leg cramps.
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Originally Posted by timtim
