June 22, 2006
Osteonecrosis of the jaw (ONJ) is an emerging condition for which no current effective treatment exists. The majority of ONJ cases, also referred to as "jaw disease," have surfaced following oral infections associated with dental procedures and are linked to individuals with osteoporosis taking oral bisphosphonates.
Initial accounts presented by scientific publications and the media have concentrated on cancer patients receiving intravenous versions of these drugs. Now scientists are learning that the oral form of bisphosphonates can also damage a patient's jaw. This class of drugs (a partial list is below) has been used to treat cancers, osteoporosis, degenerative bone disorders, and Paget's disease.
While studies are underway to better understand this condition, bisphosphonates with long latency periods are a particular concern, as the drug's latency period may delay the onset of this irreversible condition for years.
So, what does the public do in the meantime? Osteoporosis specialist, Dr. Fred K. Viren, MD, advises:
"In order to adequately caution our patients, we need to acknowledge that we are dealing with a condition characterized by a long latency period. That means that the pharmacologic effects of the oral bisphosphonates may not be seen for years, so now is the time to educate our patients."
Osteoporosis is a condition commonly treated with oral bisphosphonates. Osteoporosis is a major health risk for 44 million Americans and, presumably, as the number of osteoporosis cases rise, so will the number of bisphosphonates prescribed to treat them. While patients often receive low doses of these drugs, some bisphosphonates can remain in the system for long periods of time. The possible consequences of the long latency period are anticipated but unknown.
An estimate of how long a drug remains in the body can be given by the drug's half life. This public information may be listed on the label or found on the drug's website. It is also possible that a longer half life may result in a longer period of time prior to the onset of symptoms.
Bisphosphonate Estimated Half Life
A partial list
Boniva = 4.6-15.3 hrs for IV 2mg after 2 hrs (IV and Oral)
Boniva = 5 - 25.5 hrs for IV 4mg after 2 hrs (IV and Oral)
Bonefos = 13 hrs for IV (IV and Oral)
Aredia = 28 +/- hrs (IV and Oral)
Zometa = 146 hrs (IV)
Actonel = 480 hrs (Oral)
Fosamax = 10 years (Oral)
There is no current effective treatment for ONJ, even after the medication is withdrawn. Jaw reconstructive surgery, surgical debridements, hyperbaric oxygen therapy, reconstruction with plates, reconstruction with bone, antibiotic therapy, and other treatments have not been completely effective at eradicating the progression of necrotic bone.
Bisphosphonates work by altering the bone cycle. Under certain conditions they have led to pain, build up of fragile bone, and disfiguration of the jaw. These symptoms have now been identified as characteristics of ONJ.
Factors unique to the oral cavity that are potentially linked to ONJ's early manifestation in the mouth have included:
- The pressure exerted on bone during invasive dental procedures
- The vascular supply resulting from the antiangiogenic effects of the bisphosphonates
- The activity of the mastication muscles
- The periodontal health of the patient
- The systemic health of the patient
- The strength of the bisphosphonate
- The length of time the patient has been on the bisphosphonate
- The length of time the bisphosphonate remains in the body
As the search for effective treatment options for ONJ continue, some scientists are looking to vitamin D -- a vitamin that when prescribed properly can increase bone mass and offer patient benefits that go far beyond bone.
In recent years science has revealed that many people are vitamin D deficient and don't know it. A simple blood test can confirm this. .
During this ambivalent waiting period, it is prudent to test patients for vitamin D deficiency and discuss their current osteoporosis treatment with their physician.
*(A blood level of the vitamin below this recommendation is considered deficient.)