An update on selective estrogen receptor modulators for the prevention and treatment of osteoporosis.

Several selective estrogen receptor modulators are in clinical development for postmenopausal osteoporosis. Bazedoxifene has shown significant reductions in vertebral and non-vertebral (in higher-risk women) fracture risk, with no evidence of breast or endometrial stimulation. Lasofoxifene has demonstrated significant reductions in vertebral and non-vertebral fracture risk, but has been associated with endometrial/uterine effects. Both selective estrogen receptor modulators were generally safe and well tolerated but have been associated with some "class effects" (e.g., hot flushes, venous thromboembolic events). A tissue selective estrogen complex partnering bazedoxifene with conjugated estrogens is under clinical investigation for the treatment of menopausal symptoms and osteoporosis prevention. Future directions in selective estrogen receptor modulator research include ospemifene and RAD 1901.