The Baffling Business of Bones

Bones are getting a lot of buzz these days. For one thing, TV commercials promoting osteoporosis drugs like Boniva and Reclast create an image of healthy activity.
Watch television and you are likely to see Sally Field watering her flowers, romping with her dog or playing Twister with her grandchild while she boosts the benefits of Boniva.
Then there is the forensic anthropologist and best-selling author Kathy Reichs. The popular TV show “Bones” is based on her series of thrillers. Now Dr. Reichs is a spokeswoman for an osteoporosis awareness program called “Know My Bones.”
Not surprisingly, a pharmaceutical company is supporting this initiative. Amgen, the maker of a new osteoporosis drug called Prolia (denosumab), is hoping for rapid FDA approval.
Bones are big business. Nearly $5 billion is spent on medications like Actonel, Boniva, Fosamax (available generically as alendronate) and Reclast. These medications are known as bisphosphonates. They work by slowing the natural breakdown of bone by cells called osteoclasts. This allows bone-building cells (osteoblasts) to catch up a bit and improves bone mineral density.
Prolia also slows bone loss, but through a different approach: it prevents formation of osteoclasts so the body makes fewer of them. A new study shows that Prolia injected twice a year cut the rate of fractures of the vertebrae from about 7 percent to just over 2 percent (New England Journal of Medicine, Aug. 20, 2009).
You can tell the competition is strong by the fact that Amgen officials have been pointing out weaknesses in the Fosamax record: the drug has been linked to jaw bone death, a serious though apparently rare side effect.
Bisphosphonates are also linked to incapacitating muscle and joint pain as well as digestive tract irritation. These drugs are incorporated into bone and may make it more brittle with time. Some long-term users have recently reported broken thigh bones.
Readers have reported experiences similar to this one: “I read your column on unusual femur fractures after taking Fosomax for 5 years or more. I broke my right femur in May, 2007, and the left femur in February, 2008. I’ve taken Fosamax or Actonel for about 10 years. For four years prior to the fractures I had thigh pain for which no reason could be found.”
That doesn’t mean Amgen’s new drug is perfect, though. The committee advising the FDA was concerned about a slightly increased risk of infection and cancer among patients given Prolia.
Although bisphosphonates have the lion’s share of the osteoporosis market, there are several other strategies against osteoporosis that may be more appropriate for some people. We discuss the pros and cons of these medications and non-drug approaches in our Guide to Osteoporosis.
Since patients may be taking bone drugs for many years, they need to know the long-term benefits and risks of such medications.