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Osteoporosis Drugs Linked to Rare Fractures

Panel Wants Bisphosphonates to Have Labels Warning of Risk of Femur Fracture
WebMD Health News
Reviewed by Laura J. Martin, MD

Sept 14, 2010 -- Popular osteoporosis drugs known as bisphosphonates may increase the risk of rare, but painful thigh bone fractures, and their labeling should be updated to reflect this increased risk. That's the conclusion of a 27-person international task force that was convened by the American Society of Bone and Mineral Research to study the link between these drugs and the unusual (also called atypical) femur fractures.

The panel conducted a thorough literature review (which included published and unpublished case studies) and identified 310 such fractures. Ninety four percent of people who sustained these fractures had taken bisphosphonates for more than five years.

The findings are published in the Journal of Bone and Mineral Research. The FDA has been waiting for the report of the task force before making recommendations about bisphosphonates and the unusual fractures.

The bisphosphonate class of drugs includes Aclasta, Actonel, Aredia, Bondronat, Boniva, Didronel, Fosamax, Fosavance, Reclast, Skelid, and Zometa.

"We now believe there is a relationship between this class of drugs and this unusual thigh bone fracture, and that this relationship is stronger in patients who have taken these drugs for a longer time," says task force co-chair Elizabeth Shane, MD, professor of medicine at Columbia University in New York City.

"Still, these thigh fractures are unusual and uncommon, particularly when you view them in the context of more common osteoporosis fractures, such as rib, spine, and arm fractures," she says.

Fractures Are Rare

Unusual femur fractures actually comprise less than 1% of all hip and thigh fractures, and less than one-tenth of 1% of patients on these drugs have sustained a fracture like this, she says.

"These are uncommon fractures, but of course when you have one that doesn't matter because it is affecting you, and they can be devastating and are very serious," she tells WebMD.

"We don't want patients or doctors to be afraid to prescribe these drugs because they are worried about thigh fractures," she says. "Many, many more fractures are prevented by these drugs than are caused by them."

Taken by millions of people, bisphosphonates work by slowing the bone breakdown process. Bones are constantly breaking down and repairing themselves. The bone breakdown process quickens with advancing age, and if bone rebuilding can't keep up, bones may become brittle and more prone to fracture.

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