Sept. 9, 2011 -- Labels on bisphosphonates, a type of medication used to treat and prevent osteoporosis, should further clarify how long patients can take them, an FDA advisory panel voted today.
But the panel backed off giving any specific time limits.
Bisphosphonates include Aclasta, Actonel, Altevia, Boniva, Fosamax, and Reclast. Four million to 5 million Americans fill prescriptions for the drugs every year, according to the FDA
The FDA convened the meeting because of emerging safety concerns related to long-term use -- generally considered more than three to five years -- of bisphosphonates.
In particular, the agency has received reports of osteonecrosis, or bone death, of the jaw and unusual fractures of the femur, or thigh bone, in women who had taken the drugs for several years or more.
Meanwhile, some research suggests that because bisphosphonates remain in bone for years, women could still benefit after they stop taking them.
The panel, made up of the Advisory Committee for Reproductive Health Drugs and the Drug Safety and Risk Management Advisory Committee, voted 17 to 6 in favor of recommending additional labeling information about the drugs' long-term safety and effectiveness.
The FDA usually but not always follows its advisory committee's recommendations.
The agency's own analysis concluded that in women who continue bisphosphonate therapy after five years of use there's no clear benefit or evidence of harm and no subset of patients who have a "clear and consistent" reduced fracture risk, FDA scientist Theresa Kehoe, MD, told the panel.
Bisphosphonate labels mention that safety and effectiveness information is based on one to four years -- depending on the drug -- of clinical trial data, Kehoe said, but optimal length of use is unknown.
"This is really an issue that's front and center in primary care," said Douglas Bauer, MD, a University of California, San Francisco, primary care doctor invited by the FDA to address the advisory panel.
While not an ideal study to examine long-term use, the only published study to do so involved Fosamax, Bauer said. That study randomly assigned women who'd taken Fosamax daily for five years in a clinical trial to either continue taking the drug for another five years or stop.
For fractures other than those of the spine, there was no evidence overall of continued benefit after five years, Bauer said.
But there was a 55% reduction in spine fracture risk in women who continued taking Fosamax for the extra five years, said Arthur Santora, executive director of clinical research for diabetes and endocrinology drugs at Merck, which makes the drug.
And in studies of up to 10 years of use, Santora said, there were no reports of jawbone death and no difference in the risk of unusual thigh fractures between women who took the drug and those who didn't.