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Raloxifene (Evista) belongs to a class of drugs called selective estrogen receptor modulators (SERMs). It is FDA-approved for the prevention and treatment of osteoporosis in postmenopausal women and to reduce risk of invasive breast cancer in postmenopausal women at high risk or with osteoporosis.
SERMs were developed to reap the benefits of estrogen while avoiding the hormone’s potential side effects. Raloxifene, a so-called ”designer” estrogen, can act like estrogen on bone — protecting its density — but as an anti-estrogen on the lining of the uterus.
In a three-year study involving some 600 postmenopausal women, raloxifene was found to increase bone density and lower LDL cholesterol, while having no stimulative effect on the uterine lining (which means that it is unlikely to cause uterine cancer).
The first SERM to reach the market was tamoxifen, which blocks the stimulative effect of estrogen on breast tissue. Tamoxifen has proven valuable in preventing cancer in the second breast of women who have had cancer in one breast.
Because of its anti-estrogen effects, the most common side effects with raloxifene are hot flashes. Conversely, because of its estrogenic effects, raloxifene increases the risk of blood clots, including deep vein thrombosis (DVT) and pulmonary embolism (blood clots in the lung). Studies show that the risk of blood clots over a five year period is less than 1% for women who did not have a history of blood clots. Patients taking raloxifene should avoid tobacco use and prolonged periods of immobility during travel, when blood clots are more prone to occur.
The risk of deep vein thrombosis with raloxifene is probably comparable to that of estrogen, about 2 to 3 times higher than the usual low occurrence rate. Raloxifene also increases the risk of stroke death in women who have heart disease or risk factors for heart disease.
Raloxifene decreases the risk of spine fractures in postmenopausal women with osteoporosis, But it does not appear to decrease the risk of hip fracture. (The only agents that are definitely proven to decrease hip fracture risk are bisphosphonates.)
Another SERM combination drug, bazedoxifene-conjugated estrogen (Duavee) is FDA-approved to reduce hot flashes and osteoporosis in postmenopausal women.