True Stories: Serious complications of drugs for osteoporosis

Bones are formed, molded and absorbed continuously. Bone cells, called osteoblasts, are responsible for the new bone formation and cells known as osteoclasts absorb the bone. Osteoclast activity leads to thinning of the bones (osteoporosis), which results in fractures eventually. Around 60 years, the new bone formation slows down, osteoclast activity increases and bone thinning accelerates.

To prevent osteoporosis, doctors prescribe drugs called bisphosphonates that block the osteoclast activity. Examples of commonly prescribed bisphosphonates are alondonate sodium (Fosamax) and pamidronate disodium (Aredia).

The common side effects of bisphosphonates are loss of appetite, abdominal pain, constipation, esophageal ulcer, difficulty in swallowing and abdominal distention. Physicians prescribe these drugs for long-term use and serious side effects are being noticed currently. Reports to the Federal Drug Administration and published articles suggest occurrence of rare but serious complications in some patients.

What are these complications?

Low energy femoral fractures (e.g., falling from a standing height or less) have occurred in patients taking long-term bisphosphonates. Dr. Joseph Lane and colleagues from New York Presbyterian Hospital have noted that 15 of 41 patients (37 percent) with subtrochantric and femoral shaft fractures were on long-term bisphosphonate treatment, whereas in controls only nine had such fractures out of 82 (11 percent). Recent data suggest that these drugs may weaken collagen in the bone leading to fractures. Lane pointed out that the half-life of bisphosphonates is 10 years but the premarketing trials for these drugs were conducted for three to five years only.

To minimize the side effects, Lane gives a drug holiday if he notices that bone remodeling has stopped. After five years, he discontinues bisphosphonates and gives his patients only calcium and vitamin D. If bone loss continues, he restarts the bisphosphonates at a lower dose.

In January 2008, the FDA notified physicians that bisphosphonates had caused severe muscle and bone pain in several patients, which had developed within days, months or years after initiating treatment. Luckily, this pain subsided after stopping the drug.

The New England Journal of Medicine (2009) and Archives of Medicine (2008) have reported disturbances in heart rhythm (atrial fibrillation) with bisphosphonates. However, the FDA has analyzed 19,358 patients on bisphosphonates and concluded that there is no link between these drugs and AF. An exception is zoledronic acid; its use is definitely associated with increased risk for AF.

Several dentists in 2006 noted jawbone degeneration in several patients using bisphosphonates. Dr. Parish Sedghizadeh has analyzed 208 dental patients who were on long-term bisphosphonates; out of them, nine (4 percent) had necrosis of their jawbone. Sedghizadeh has eliminated this complication by taking steps to reduce oral bacteria and consulting the patient’s physician to start bisphosphonates after the dental procedures have been completed. However, more studies are needed to confirm the connection between the bisphosphonates and jaw necrosis.

Another dreaded complication is the development of esophageal cancer in patients taking Bisphosphonates. The FDA has received 23 reports of esophageal cancer including eight deaths between the years 1995 and 2008. In Japan and Europe such a connection was noted as well. More studies are needed to clinch this association.

If you are on bisphosphonates such as Fosamax or Aredia on a long-term basis, please talk to your doctor about their potential complications, tests to detect them and possible drug holiday.

— Dr. Raghavendra Rao is a pediatrician in Porterville. He writes periodically for The Recorder. An article in the Journal of Medical Association, Feb. 18, 2009 is the basis for the above commentary.