Pharmacologic prevention of osteoporotic fractures.

Osteoporosis is characterized by low bone mineral density and a deterioration in the microarchitecture of bone that increases its susceptibility to fracture. The World Health Organization defines osteoporosis as a bone mineral density that is 2.5 standard deviations or more below the reference mean for healthy, young white women. The prevalence of osteoporosis in black women is one half that in white and Hispanic women. In white women 50 years and older, the risk of osteoporotic fracture is nearly 40 percent over their remaining lifetime. Of the drugs that have been approved for the prevention or treatment of osteoporosis, the bisphosphonates (risedronate and alendronate) are most effective in reducing the risk of vertebral and nonvertebral fractures. Risedronate has been shown to reduce fracture risk within one year in postmenopausal women with osteoporosis and in patients with glucocorticoid-induced osteoporosis. Hormone therapy reduces fracture risk, but the benefits may not outweigh the reported risks. Teriparatide, a recombinant human parathyroid hormone, reduces the risk of new fractures and is indicated for use in patients with severe osteoporosis. Raloxifene has been shown to lower the incidence of vertebral fractures in women with osteoporosis. Salmon calcitonin is reserved for use in patients who cannot tolerate bisphosphonates or hormone therapy.