Jaw Disease Risk may increase with Bone-Growth Drugs

According to a new study bone building drugs for people suffering from osteoporosis could increase the risk of developing a jaw infection. The jaw disease called osteonecrosis of the jaw (ONJ) and is characterized by pain, soft-tissue swelling, infection, loose teeth and exposed bone.

Bisphosphonates are prescribed for people with osteoporosis and used to reduce the risk of bone fracture and to increase the bone mass. It is also used to slow bone "turnover" in people who have cancer that has spread to their bones, and in people who have the blood cancer multiple myeloma. Alendronate (Fosamax), ibandronate (Boniva) and risedronate (Actonel) are some commonly prescribed bisphosphonates.

Earlier reports had said indicated that the risk of developing ONJ from bisphosphonates taken in pills was "negligible," though people taking the higher-dose intravenous form of the drug had a noted risk for the disease.

Study coauthor Parish Sedghizadeh, an assistant professor of clinical dentistry and researcher at the University of Southern California in Los Angeles said jawbone disease is "absolutely rare, and one of the least likely bones to get infected. All of a sudden, we saw this raging epidemic of jawbone infections," prompting the researchers to sit up and take note.

They checked out the electronic medical records of dental patients at USC. The researchers found that nine out of 208 patients or 4 % who were taking Fosamax, the most widely prescribed oral bisphosphonate, had active ONJ and all of them had undergone some kind of dental procedure, such as having a tooth removed. None of the 13,522 control patients, who were not taking the bone-building drugs, were diagnosed with jawbone necrosis. This led the study authors to conclude that patients on Fosamax for as little as one year have had jaw complications and seems to occur most frequently after routine tooth extraction.

Merck, the maker of alendronate conducted clinical trials involving more than 17,000 patients and found no reports of jaw osteonecrosis, according to a statement released by the company in 2007.

In response Sedghizadeh said, "Better, larger studies are really needed to clarify the risk."

Dr. James Liu, chairman of obstetrics and gynecology at MacDonald Women's Hospital at Case Medical Center, University Hospitals in Cleveland, said the finding "does not mean that women should stop taking the drug if they're on it. It does mean that there may be more frequent side effects than was previously known."

The researchers don't know why the bisphosphonates only affect the jaw bone though Sedghizadeh feels it could be because the drugs make it easier for bacteria to stick to bones that are exposed after a tooth extraction.

Sedghizadeh recommends that patients on these bone-building drugs be classified as "at-risk" for developing jawbone infections after dental procedures till further studies can establish the exact cause. "As a school now, we don't have complications any more, we only have referrals," Sedghizadeh said. "We put patients on anti-microbial, anti-fungal rinse one week pre-operatively or post-operatively. If they have been on bisphosphonates six months or a year or longer, then we have a prevention protocol which has been very, very effective."

Merck & Co., which makes Fosamax, in a statement, said the new study "has material methodological flaws and scientific limitations, making it unreliable as a source for valid scientific conclusions regarding the prevalence of ONJ in patients taking alendronate." The results appear January 1 in the Journal of the American Dental Association.

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