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Less Is More (Bone): Yearly osteoporosis drug reduces fractures

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6:48pm, May 1, 2007
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Older women with osteoporosis who received yearly infusions of a drug that prevents bone loss had far fewer fractures than did peers who didn't get the drug.

Over 3 years, the women who received zoledronic acid intravenously had about one-third as many spine fractures as did women who received a placebo. The drug-treated group also had significantly fewer fractures of the hip, wrist, and other bones.

"I think [the findings] will change clinical practice, particularly for the oldest people, who are most at risk" for fractures, says Dennis Black of the University of California, San Francisco. He led the study published in the May 3 New England Journal of Medicine.

Most current osteoporosis drugs must be taken orally every morning or once a week on an empty stomach and with a full glass of water. To avoid esophageal irritation, patients must remain upright for 30 minutes after taking their pills.

Black says that about 70 percent of people prescribed oral bisphosphonates fail to follow that strict regimen. However, with an annual infusion of drug, "you'll have 100 percent adherence for a year," he says. "And that means the clinical effect, the real ability to reduce fractures, goes way up."

The Food and Drug Administration approved intravenous zoledronic acid in 2002 for the prevention of the spread of certain cancers to bones. Almost immediately, physicians began administering the drug intravenously for osteoporosis, says Andrew Stewart of the University of Pittsburgh Medical Center. "This study is good news for doctors who thought they were doing the right thing" when recommending zoledronic acid beyond the uses listed on its label, he says.

Bisphosphonates work by seeping into the mineral lattice of bones. After intravenous administration of the drug, "the bone serves as its own reservoir and releases [the drug] continuously over the year," says Stewart. Taken orally, however, only 1 to 2 percent of the drug finds it way into the bone, so patients have to take it frequently.

The 3-year study—funded by the maker of zoledronic acid, Novartis—followed nearly 8,000 women with osteoporosis. Half received yearly 15-minute infusions of zoledronic acid, and half received saline infusions.

At the end of the study, 92 women receiving the drug and 310 women receiving saline had cracks in their vertebrae revealed by X rays. Fifty-two women in the drug group and 88 in the saline group had suffered hip fractures. Bone density increased in the drug group but not in women getting the placebo.

Zoledronic acid's reduction of fractures is comparable to or slightly better than the effect seen with the three other bisphosphonates approved for osteoporosis, both Stewart and Black say.

One of these drugs can be taken in a monthly oral dose, but zoledronic acid is the first such drug studied as a yearly infusion. The success of the regimen makes it attractive for patients who have difficulty following an oral-medication schedule, the researchers assert. Says Black, "Some people will say, 'This is great. I can go to my doctor once a year, and I don't have to think about it again.'"

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