Fosamax and Risk of Osteonecrosis of the Jaw

Fosamax (generic name alendronate) is the most popular drug of a class of drugs called bisphosphonates that are used to treat a variety of conditions affecting the bones. Fosamax itself is primarily prescribed to combat osteoporosis, bone loss that makes the bones fragile, and osteopenia, a less severe thinning of the bones. With 190 million Fosamax prescriptions dispensed worldwide, it is important to know what the risks of taking Fosamax are and what negative side effects are associated with taking Fosamax long term.

Beginning in 2004, the drug company Novartis issued a warning of a link between intravenous bisphosphonates and osteonecrosis of the jaw. In 2005, that warning was broaded to include oral bisphosphonates like Fosamax. The medical community was initially divided on whether Fosamax and other oral bisphosphonates could cause osteonecrosis of the jaw (ONJ), but according to a 2009 Position Paper from the American Association of Oral and Maxillofacial Surgeons (AAOMS), the evidence is now relatively strong that some cases of ONJ are in fact due to oral doses of bisphosphonates.

What Are the Risks?

As just mentioned, the big concern in recent years has been with bisphosphonates causing osteonecrosis of the jaw (ONJ) or, literally, jaw death or jawbone death. ONJ is essentially a condition where bone in the jaw is exposed and refuses to heal for a long time. The American Association of Oral and Maxillofacial Surgeons considers a patient to have ONJ caused by bisphosphonates if all three of these criteria are met:

There are however other medical conditions that can be confused with ONJ from bisphosphonates. These "commonly misdiagnosed conditions can include, but are not limited to, alveolar osteitis, sinusitis, gingivitis/periodontitis, caries, periapical pathologic findings, and temporomandibular joint disorders." It is important to get a correct diagnosis from a qualified oral surgeon.

The AAOMS considers that emerging studies "have established a firm foundation for a strong association between monthly IV bisphosphonate therapy and the development of BRONJ [bisphosphonate-related osteonecrosis of the jaw]." Note, however, that the conclusion only concerns intravenous doses of bisphosphonates, usually used in cancer treatment, and does not include oral bisphosphonates used to treat osteoporosis.

Is Fosamax Dangerous?

Here's where things get more difficult. There are documented cases of ONJ being associated with treatment with oral bisphosphonates. However, there is still not great evidence about how strong the cause and effect relationship is. Merck, the manufacturer of Fosamax (alendronate), has estimated that the incidence of ONJ related to alendronate is 0.7 cases per 100,000 patient years. In other words, you would expect that for every 143,000 patients taking Fosamax for a year, one patient would get ONJ because of taking Fosamax. A study of 13,000 Kaiser Permanente patients who were long-term users of Fosamax estimated 0.06% of patients, or one patient for every 1,700 on Fosamax, would get ONJ at some point. Studies in Germany and Australia found generally lower risks.

Patients have to balance the risks taking a prescribed bone-densifying agent against the risk of breaking a bone weakened by osteoporosis or cancer. So, no patient should discontinue bisphosphonate therapy without consulting his or her medical team.

Safety Measures and Precautions

While ONJ can happen spontaneously or after minor trauma, most documented cases of ONJ related to oral bisphosphonates are in patients who are long-term users or have had oral surgery.

Given that, the AAOMS recommends the following: