by Cooper B. Wilhelm
Bisphosphonates are a staple of osteoporosis treatment. However, a recent study has added to a growing pool of data linking the prolonged use of bisphosphonates to unusual thigh fractures. This comes less than two weeks after an FDA analysis that undermines the long-term efficacy of bisphosphonates was summarized in The New England Journal of Medicine. The solution may be a “drug holiday.”
Bisphosphonates are a group of drugs that includes many common treatments for osteoporosis, such as ibandronate (brand name Boniva), alendronate (Fosamax), risedronate (Atelvia, Actenol), and zoledronic acid (Reclast).
A study of fracture statistics over 12 years at a major hospital in Geneva, Switzerland, showed that although the incidence of so-called atypical fractures was still very low, it was strongly linked to bisphosphonate use. Excluding people who had sustained fractures after events such as car accidents or falls from greater than standing height, researchers grouped study subjects into two sets: those who had had atypical fractures and those who had had common, or “classic,” fractures. Of the people who had had atypical fractures, 82.1% had been treated with bisphosphonates at some time, as opposed to only 6.4% of those with classic fractures.
This would seem to corroborate the findings of a similar study presented at the 2010 meeting of the American Society for Bone and Mineral Research. Looking at HMO records from 15,000 femur (thighbone) fractures, researchers identified 102 individuals as having had atypical fractures. Of those people, 95% had taken oral bisphosphonates. That study also found that the risk of atypical fractures increased the longer people took the drugs.
And although the risks associated with bisphosphonates may rise over time, a background summary recently provided to an FDA advisory committee suggests that their efficacy decreases. According to the FDA review, while people using bisphosphonates may experience continued bone density and strength increases in their spines and maintained increases in their necks for 10 years or more, there does not seem to be much of an increase for bones in other parts of the body after 3–4 years. There was some evidence to suggest taking bisphosphonates longer would bring added benefits, but data also indicate that stopping bisphosphonate treatment after 3–5 years would not greatly increase overall risk of classic fractures.
A review published in The Archives of Internal Medicine pointed out that this efficacy data was only from two trials of two bisphosphonates and may not be representative of the drug class as a whole. However, given this apparent plateauing in benefits from the drugs, combined with the increased risk of atypical fractures with prolonged use, that review echoed the FDA briefing’s suggestion that consideration be given to taking breaks from bisphosphonates. More testing would be needed to determine who would benefit most from such a “drug holiday” and how long it should last.
Last Reviewed May 31, 2012
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