Jaw Damage Linked to Bisphosphonates
Monday, November 10th, 2008For several years medications prescribed to combat osteoporosis have been linked to a widely publicized condition in which jawbone tissue dies. Dr. Thomas B. Dodson explains: “Bisphosphonate-related osteonecrosis of the jaw’ is a mouthful.” His expertise is oral and maxillofacial surgery at Massachusetts General Hospital. He’s an expert on, let’s just call it BRONJ.
The problem has been linked to drugs called bisphosphonates, ranked 10th in U.S. sales among all drug categories, according to IMS Health, which analyzes pharmaceutical and health care markets. The majority of cases come after someone has been treated for cancer with potent, intravenous forms of the drugs. About 1 in 10 cancer patients treated with IV bisphosphonate develops the jaw problem.
But a handful of cases have shown up in women taking much smaller doses of the drugs for treatment of osteoporosis.
Bisphosphonates marketed as Actonel, Aredia, Boniva, Didronel, Fosamax, Reclast, Skelid, Zometa and others are meant to increase bone density in the short run by reducing the bone-loss part of the bone life cycle. But some scientists think the drugs may eventually hurt the jaw’s ability to heal after, say, a tooth extraction.
The estimates on the number of people who might experience the jaw problem range from 1 in 2,000 to as many as 1 in 300 people who take the drugs for osteoporosis. In the U.S., 55 million prescriptions for bisphosphonates are written annually, according to a 2007 report in the journal Osteoporosis International.
Most commonly, people with problems will see or feel some exposed bone in the mouth, as the dead bone works its way through gum or tissue, but without pain. In those cases, people are simply told to use an antibacterial mouthwash. If there’s pain or discomfort, and the area of exposed bone is small, a dentist will try to smooth down the exposed area.
In rare cases, the area of dead bone is large. “Then people run the risk of breaking the jaw, because the area is so large,” Dodson says.
So why would a medicine that circulates through the body result in a pharmaceutical punch to the jaw? It could be, Dodson says, that bone in the jaw metabolizes at a speedier rate than in other parts of the body, resulting in more of the drug being deposited there. Because there is more bacteria in the mouth area, that could add to inflammation and worsen the problem.
Or it could be, he says, that the mechanism of the drug is at work. Bisphosphonates inhibit cells that dissolve bone. “But dissolving bone is part of a healthy life cycle,” he says.
The natural balance between dissolving bone and making new bone is disrupted, and bone-producing cells now dominate. But when they die off, there are fewer cells to clean them out, so they remain, a dead mass.