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Osteoporosis Drugs' Safety Subject of FDA Panel
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FRIDAY, Sept. 9 (HealthDay News) -- Experts convened by the U.S. Food and Drug Administration were to meet Friday to discuss problems linked to long-term use of bone-building drugs such as Fosamax, Actonel, Boniva and Reclast.
These drugs, known as bisphosphonates, are taken to prevent fractures related to postmenopausal osteoporosis. But researchers have linked long-term use with a small risk of unusual fractures of the thigh bone, death of the jawbone (osteonecrosis of the jaw) and possibly esophageal cancer.
Members of two FDA advisory committees are expected to weigh the drugs' risks and benefits and possibly come up with new recommendations regarding their use. According to the FDA, in 2009 more than 5 million prescriptions were filled for bisphosphonates, which inhibit bone loss.
Dr. Elizabeth Shane, past president of the American Society for Bone and Mineral Research, who is scheduled to testify before the committee, said reports linking bisphosphonates with atypical fractures and osteonecrosis of the jaw are "extremely rare, when considered in the context of how many people take bisphosphonates for osteoporosis." She was "less certain about the esophageal cancer issue," she added.
While these side effects shouldn't be downplayed, "when you consider the number of very dangerous, life-threatening fractures that are prevented by these drugs, the benefits dwarf the side effects," said Shane, also a professor of medicine at Columbia University in New York City.
However, she said bisphosphonates should only be prescribed to those at the highest risk of fracture. "In the past we might have used them in people who aren't at such high risk of fracture in the hope that they would prevent fractures down the line," she said. "We have moved to targeting people at high short-term risk, which means in the next five to 10 years."
According to Shane, the absolute risk of developing osteonecrosis of the jaw is between 1 in 10,000 and 1 in 400,000 among people taking these drugs for osteoporosis.
But when high-dose bisphosphonates are used to slow the spread of bone cancer, the risk rises, affecting anywhere from 1% to 15% of patients, she said.
For atypical femur (thigh) fractures, the absolute risk linked to bisphosphonates is about 1 to 5 fractures in 10,000 bisphosphonate users, she said.
Besides hip fractures, bisphosphonates prevent spine, wrist and arm fractures, Shane said.
The FDA wants the committee to consider whether current data support long-term use of bisphosphonates for treating or preventing osteoporosis. The experts also are to consider whether a time limit should be placed on their use, and if patients who need long-term therapy would benefit from a "drug holiday," meaning time off the medication.
"I am really not in favor of putting a limit on use of bisphosphonates and dictating the use of drug holidays," Shane said. "We have very little evidence to support the use of drug holidays or no drug holidays."
If the committee finds that bisphosphonates do pose a serious risk, it may suggest revising the drugs' labels to reflect these potential dangers. The labels already carry a warning about atypical femur fractures.
Dr. Nelson Watts, director of the University of Cincinnati Bone Health and Osteoporosis Center and co-author of a 2010 study on long-term use of bisphosphonates, said length of treatment should be considered on an individual basis. His study suggested patients at mild risk might discontinue drug treatment after five years for as long as no fractures occurred and no bone loss was evident. Higher-risk patients could take the drugs for 10 years and perhaps then take a "holiday" from bisphosphonates of one or two years.
"It would probably be helpful if FDA or some official organization could provide guidelines on duration of treatment, details of drug holidays, etc., but there is probably not enough information in the literature for recommendations based on science," Watts said.
Unusual bone problems aren't limited to patients taking bisphosphonates, another expert said. "Osteonecrosis of the jaw and atypical fractures of the femur also occur in patients not taking bisphosphonates," said Dr. Silvina Levis, a professor of medicine and director of the Osteoporosis Center at the University of Miami Miller School of Medicine. "These events are very rare in patients with osteoporosis, and the benefits of these drugs outweigh the risks."
Common bisphosphonates are taken in tablet form or by injection. They include: Fosamax (alendronate sodium) made by Merck & Co., Inc.; Actonel and Atelvia (risedronate sodium) made by Warner Chilcott; Boniva (ibandronate sodium) from Roche Therapeutics, Inc.; and Reclast (zoledronic acid) from Novartis Pharmaceuticals Corp.
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SOURCES: Elizabeth Shane, M.D., past president, American Society for Bone and Mineral Research, endocrinologist and professor of medicine, Columbia University, New York City; Silvina Levis, M.D., professor of medicine, director, Osteoporosis Center, University of Miami Miller School of Medicine; Nelson B. Watts, M.D., director, University of Cincinnati Bone Health and Osteoporosis Center, Cincinnati, Ohio