Selective estrogen receptor modulators (SERMs)

Raloxifene (Evista)

Raloxifene (Evista) belongs to a class of drugs called selective estrogen receptor modulators (SERMs). SERMs work like estrogen in some tissues but as an anti-estrogen in other tissues. The SERMs are developed to reap the benefits of estrogen while avoiding the potential side effects of estrogen. Thus, raloxifene can act like estrogen on bone, but as an anti-estrogen on the lining of the uterus.

The first SERM to reach the market was tamoxifen, which blocks the stimulative effect of estrogen on breast tissue. Tamoxifen has proven valuable in women who have had cancer in one breast in preventing cancer in the second breast. Raloxifene is the second SERM to be approved by the FDA. Raloxifene has been approved for the prevention and treatment of osteoporosis in postmenopausal women. 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).

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). The greatest increase in risk occurs during the first 4 months of use. Patients taking raloxifene should avoid 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 decreases the risk of spine fractures in postmenopausal women with osteoporosis, but the benefit in decreasing hip fracture risk is not yet known. (The only agents that are definitely proven to decrease hip fracture risk are bisphosphonates.) For more, please read the Evista drug information article.