When is Enough Fosamax Enough?

The bisphosphonates (alendronate or Fosamax®, risedronate or Actonel®, and pamidronate or Aredia®, among others) have saved thousands, if not millions of women from severe fractures. In recent months, however, there is increasing evidence that long-term Fosamax use may actually increase the risk of one type of fracture of the femur. It’s thought that prolonged Fosamax may over-suppress bone metabolism, allowing microscopic damage of the bone to proceed to a fracture.

Writing in the Journal of Orthopaedic Trauma, Cornell University scientists report on their analysis of all 70 patients with femoral shaft fractures admitted to their trauma center between 2002 and 2007. (Note that this site – the femoral shaft – is different from the much commoner site for femoral or hip fractures – the neck of the femur.) The average age of the patients was 75, and 59 of them were women. And 25 (36%) of them were being treated with Fosamax at the time of their fracture.

Nineteen of the 25 patients taking Fosamax had a simple, transverse fracture in an area of increased thickness of the shaft of the femur; this fracture pattern was seen in only one patient not taking Fosamax.

The average duration of Fosamax use was significantly longer in the shaft fracture patients than in those without this type of fracture – 6.9 years versus 2.5 years. Only one patient with the shaft fracture pattern had been taking Fosamax for less than 4 years.

Why were there no shaft-fracture patients found to have been taking other bisphosphonate drugs? Is it a specific risk of Fosamax, compared to one from other bisphosphonates? Or is it because Fosamax has been available for several years longer than its nearest rivals in this class of drugs? Time will tell. But in the meantime, physicians may want to consider discontinuation of Fosamax after 5 years’ continued use . . .