How and Why Fosamax Causes Osteonecrosis of the Jaw (ONJ)
Serious Jaw-bone Condition Can Develop Even Years After Person Stops Taking This Osteoporsis Medicine
In July 2005 Merck finally revised the Fosamax label, or package insert, to include a warning about osteonecrosis of the jaw (also known as ONJ).
In an article entitled "Bisphosphonate-induced exposed bone of the jaws", Robert Marx, MD provides this insight about why the jaw bone, in particular, is susceptible to ostenecrosis, or "bone death":
Because the jaws have a greater blood supply than other bones and a faster bone turnover rate related both to their daily activity and the presence of teeth (which mandates daily bone remodeling around the periodontal ligament), bisphosphonates are highly concentrated in the jaws. Coupled with chronic invasive dental diseases and treatments and the thin mucosa over the bone, this anatomic concentration of bisphosphonates causes this condition to be manifested exclusively in the jaws.
Dr. Marx, who is chairman of the division of oral and maxillofacial surgery at Florida's University of Miami, said in May 2006 that he is aware of at least 40 or 50 cases of ONJ nationwide in patients who had taken Fosamax. According to Dr. Marx:
The concentration [of bisphosphonates] in the bones begins to build up by the third year. So it's not surprising that we're starting to see more cases [of ONJ] among people who take the pills.
To put Dr. Marx's comments into context, although approved by the FDA in 1995, Fosamax prescriptions increased sharply starting in 2001 and is now the world's best-selling osteoporosis medication. Remarkably, more than 22 million Fosamax prescriptions were written by U.S. doctors in 2005.
Moreover, Fosamax and other bisphosphonates remain in the bone for many years. Drawing, again, from the 2005 medical journal article by Dr. Marx:
Given that it has a half-life of more than 10 years, the current widespread use of alendronate [i.e., Fosamax] to prevent or treat early osteoporosis in relatively young women and the likelihood of long-term use as well as the unbiquitous presence of dental disease in our society gives us cause for concern.
Significantly, however, no one knows how long the osteonecrosis risk remains in patients who use Fosamax or similar drugs. What this means, unfortunately, is that a person can develop this serious jaw-bone condition even years after they have discontinued their use of Fosamax.
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