A new study adds further evidence to the growing scientific consensus about the link between atypical femur fractures with Fosamax and other similar osteoporosis drugs, with the risk increasing the longer patients use the medications.
Researchers with the University of California San Francisco presented findings of a nationwide study on the link between a class of drugs known as bisphosphonates and atypical femur fractures at the annual meeting of the American Society for Bone and Mineral Research, which was held virtually from September 11 through 15.
Fosamax is the most widely used medication in this class, introduced by Merck for treatment and prevention of osteoporosis, but now widely available as generic alendronate sodium. While the drug has been used by millions of individuals strengthen bones and reduce the risk of fractures associated with osteoporosis, it has been linked to a number of side effects, including bone fractures and osteonecrosis of the jaw.
The latest findings involved a nationwide study of bone fractures among adults in Denmark, finding that the highest risk of atypical femur fractures appears to be linked to more than five years of bisphosphonate use.
According to the findings, adults over the age of 50 using Fosamax and similar drugs for 5-7 years were more than 35 times more likely to experience an unusual fracture of the femur, the thickest bone in the human body, than those who did not take the drugs. That risk increased to nearly 40 times the risk for those who used bisphosphonates for seven years or longer.
Overall, 58% of those who suffered atypical femur fractures reported bisphosphonate exposure, as did 19% of the non-atypical fracture subjects and just under 10% of the healthy control group.
Fosamax was specifically the drug used by 85% of bisphosphonate patients who participated in the study.
The researchers emphasized, however, that the absolute risk was still low, under five incidents out of 10,000 person-years. The findings are considered preliminary until published in a peer-reviewed journal.
Merck faces hundreds of Fosamax lawsuits filed by users who suffered sudden femur fractures allegedly caused by side effects of the medication, typically occurring with little or no trauma.
Plaintiffs have alleged the drug maker knew about the bone fracture risk with Fosamax, but withheld information from consumers and the medical community until the FDA required a label update in late 2010.
Merck has attempted to defend the litigation by arguing the failure to warn claims are preempted by federal law, maintaining that the FDA would not have allowed an earlier warning update, since the agency previously rejected a proposed label update about the risk of “stress fractures”.
In 2014, the U.S. District Judge Joel Pisano granted the drug makers motion for summary judgment, dismissing all Fosamax fracture claims involving injuries that occurred before a label update in September 2010. However, late last year, following a Supreme Court ruling, that decision was overturned and hundreds of Fosamax cases were reinstated and sent back to federal court.