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Osteoporosis drug has lasting effect, study says

Benefits are seen 5 years after use

WASHINGTON -- The most commonly used osteoporosis drug protected most women from broken bones for five years after they stopped using it, indicating they can take a break from it without losing benefits, a study found.

Researchers at the University of California San Francisco tracked 1,099 elderly women taking alendronate, sold by Merck & Co. as Fosamax, to treat and prevent osteoporosis, which makes bones brittle and susceptible to breaks. The study was funded by Merck.

Some took it for 10 years while others took it for five and then got a placebo for the next five years.

The study, which appeared yesterday in the Journal of the American Medical Association, found that women who took the drug for five years and then stopped for five years had moderate bone density loss compared to those who took it for 10 years. But the bone fracture rates for both groups were basically equal.

The exception was for spine fractures, the study found, with the risk of these significantly higher among the women who discontinued taking the drug after five years. Researchers said women at the highest risk for spine fractures probably should continue taking the drug without stopping.

"The main message is that if you start this particular osteoporosis therapy you may not have to take it forever. You may be able to take it for a while, then stop, and then take it again and stop," Dennis Black, the lead researcher, said in a telephone interview.

"It's good news for patients because it means they're not committing to a lifetime of pills, in terms of inconvenience and cost, and they're still going to get some benefit."

Millions of post-menopausal women worldwide take alendronate, designed to strengthen bones and prevent fractures. But doctors did not know how effective it was when used long term or whether it remained safe when taken for years.

Black said there had been some concern that using alendronate for a long time might start to weaken bones. "We didn't show any evidence of that at all," Black said.

Having tracked the women for 10 years, the study found no negative effects from continued use of the drug and saw residual effectiveness for five years after the women stopped using it.

"A woman who doesn't have a history of fracture and has only moderately low bone density might be a candidate to stop therapy for a while," Black said, while acknowledging "a big gray area" in deciding who might need indefinite use.

Alendronate is a type of drug called a bisphosphonate, the most commonly used treatment for post-menopausal osteoporosis.

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