Bisphosphonate Bone Fracture Warnings Issued in Canada

Canadian health officials are warning citizens of that country that side effects of Fosamax, Actonel and similar bone drugs may increase the risk of rare thigh bone fractures.  

Health Canada issued a bisphosphonates warning on Monday, indicating that it had reviewed the safety of the class of medications and found that there was an increased risk of atypical femur fractures. However, the overall risk was very small.

New label warnings reflecting the increased risk of bone fractures from bisphosphonates will be placed on Canadian bottles of all medications included within the class, such as Fosamax, Didrocal, Actonel and Aclasta. 

Atypical thigh bone fractures occur in less than one percent of all hip and femur fractures. They usually occur with little or no actual trauma to the legs. Health Canada has determined that bisphosphonates double that risk.

In the United States, the FDA is still weighing the recommendations of an advisory panel which met in September to discuss Fosamax femur fracture side effects. That panel voted 17 to 6 to recommend that the FDA require drug makers to provide more information about the risks and benefits associated with all bisphosphonates, including the atypical femur fractures and osteonecrosis of the jaw (ONJ). 

The panel left how those warnings should be worded up to the FDA. While the federal drug regulatory agency is not required to follow the advice of their advisory panels, it is usually heavily influenced by the recommendations.

In October 2010, the FDA required warnings about the risk of thigh fractures from Fosamax and other bisphosphonate medications be placed on U.S. labels, but the decision was based off of preliminary findings. During a review of the potential Fosamax side effects, the FDA determined that the risk of fractures of the thigh bone may be connected to long-term use of bisphosphonates.

Merck & Co. currently faces hundreds of Fosamax fracture lawsuits that have been filed by individuals who claim the drug maker failed to adequately warn about the potential risk of problems. Complaints allege that side effects of Fosamax may weaken the ability of the femur bone to repair itself from microdamage, increasing the risk of a sudden femur fracture.