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Effects of Osteoporosis Drug Treatment May Take Two Years or Longer

Some women who take prescription drugs to rebuild their bone density after menopause may not see the effects for two years or longer. An analysis of two studies published in the Journal of the American Medical Association shows that long-term drug treatment with raloxifene or alendronate  does benefit the majority of women with osteoporosis, a degenerative bone disease. However, bone mineral density (BMD) test results, which are generally used to monitor osteoporosis treatment, are not always precise and sometimes do not show improvement until the second or third year of testing. Researchers urge women to keep taking their prescribed drugs for osteoporosis even though the benefits may not be noticeable for some time.

U.S. researchers analyzed data from two large clinical studies which evaluated the relationship between the osteoporosis drugs, raloxifene (trade name, Evista) and alendronate (trade name, Fosamax), and BMD measurements. Over 10,000 post-menopausal women with osteoporosis were studied. While the majority of women in both studies did experience significant improvements in BMD during the first and second years of drug treatment, 354 women (approximately 3.5%) lost 4% or more of their bone density. However, the women continued their treatment and during the second year, 92% of women on alendronate and 79% of women on raloxifene experienced significant gains in BMD.

Ironically, women who gained the most bone density during their first year of drug treatment experienced small losses in BMD during the second year of continued treatment, according to researchers. Lead researcher Dr. Steven R. Cummings of the University of California-San Francisco and his colleagues said that drug treatment should be continued in osteoporosis patients who lose BMD during the first year because most patient with make significant gains with continued treatment.

According to Dr. Cummings, BMD testing is not 100% accurate. Though the test is useful in diagnosing osteoporosis and monitoring treatment, test results could vary in some instances from equipment imperfections or patient circumstances. BMD testing methods involve taking dual energy x-rays (DEXA) or CT scans (Osteo CT or QCT) of bones in the spinal column, wrist, arm or leg to measure the amount of calcium present.

Osteoporosis affects roughly 25 million Americans, mostly post-menopausal women, and is currently one of the most under-diagnosed and under-treated disorders in medicine. It is estimated that one-third of women over age 50 have osteoporosis. Osteoporosis is characterized by a decrease in normal bone density due to the loss of calcium and collagen. A loss of bone density causes bones to become brittle, and in turn, leads to frequent fractures and other serious effects.

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