Bone Density Medications: Friend or Foe?

Many autoimmune patients are prescribed prednisone to suppress the immune system response in order to reduce inflammation and pain. Unfortunately, regular use of prednisone for a few years leads to osteopenia (lower than normal bone density) or even osteoporosis (bone loss at risk for fractures). Physicians with osteoporotic patients will usually prescribe a medication to combat this bone loss. Actonel (risendronate), Boniva (ibandronate) and Fosamax (alendronate) belong to a class of drugs called bisphosphonates, which are designed for this purpose.

Bones are living tissue, and are constantly undergoing a regenerative process. Osteoclasts are bone cells which destroy and remove old or dead bone tissue, while osteoblasts are cells which create new bone tissue. Bisphosphonates work by inhibiting the work of osteoclasts, so no bone tissue is removed, but only generated by the osteoblasts.

On the surface, this seems to be a good way to generate more bone tissue faster, helping to stop and even possibly reverse the osteoporosis damage caused by prednisone. Research studies have shown that this process is actually quite harmful, and that these drugs may not be as useful as initially thought.

It has been found that bisphosphonates can lead to osteonecrosis of the jaw. This is a condition in which bone tissue dies and the jaw bone can possibly collapse. About 60% of these cases were preceded by dental surgical procedures that involved bone, and it has been recommended that bisphosphonate treatment be postponed until after such dental work to eliminate any potential sites of infection.

The mechanism of action by inhibiting osteoclasts does not actually increase bone density. Osteoporotic bone has less mineralization than normal density bone. Since bone density is measured by dual energy x-ray absorptiometry, this technology shows an apparent increase in density. This is because older bone is more dense than newer bone, there is less water and more mineral in the bone, therefore the DEXA scan will show increased density.

As bone mineralization increases with use of bisphosphonates, so does accumulation of microdamage. Therefore, continual usage of these drugs will actually cause brittle bones. Damage can’t be repaired since the osteoclasts are no longer functioning during use of the drugs.

These drugs also stay in the body for years after discontinuation. This can present dangers in women who are still in childbearing years and may wish to still have children.

This leads to yet another medication problem. Physicians may also try to prescribe a pharmaceutical grade vitamin D supplement at a very high dose. These usually come in 50,000 IU doses, but are in the form of vitamin D2, not D3. Vitamin D2 is not as effective as D3 in humans. It is not absorbed as well in the body. The body will synthesize Vitamin D3 through exposure to sunlight. Approximately 5-30 minutes of sun exposure mid-day at least twice a week without sunscreen will lead to sufficient synthesis.

As harmful as these bisphosphonate drugs can potentially be, it may be best to find alternate ways to try to stop or reverse bone loss. It may be better if patients could try to rebuild density by taking vitamin D3, engage in strength training exercises and take a good citric acid based calcium supplement.

References
Bisphosphonates and Osteonecrosis of the Jaws Woo SB, Hellstein JW, Kalmar JR
Ann Intern Med. 2006 Aug 1;145(3):235

Osteonecrosis of the Jaw – Do Bisphosphonates Pose a Risk? John P. Bilezikian, M.D.
N Engl J Med 2006; 355:2278-2281

Atypical subtrochanteric and diaphyseal femoral fractures: Report of a Task Force of the American Society for Bone and Mineral Research. Journal of Bone and Mineral Research, 25: 2267–2294. doi: 10.1002/jbmr.253

Editorial: Long-Term Safety of Bisphosphonates Susan M. Ott J. Clin. Endocrinol. Metab. 2005 90:1897-1899, doi: 10.1210/jc.2005-0057

Vitamin D2 Is Much Less Effective than Vitamin D3 in Humans Laura A.G. Armas, Bruce W. Hollis and Robert P. Heaney J. Clin. Endocrinol. Metab. 2004 89:No 11:5387-5391 doi:10.1210/jc.2004-0360

Dietary Supplement Fact Sheet: Vitamin D Office of Dietary Supplements National Institutes of Health
http://ods.od.nih.gov/factsheets/VitaminD/

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