Do bone density drugs really prevent fractures?
Q. Do bone density drugs really prevent fractures, and what are their benefits and risks?
A. Bones may seem like inert objects but their tissue is constantly being broken down and rebuilt. When the loss of bone begins to outpace the formation of new bone tissue, the result is osteoporosis. The primary drugs used to treat osteoporosis are bisphosphonates. There are currently four approved drugs in this class: alendronate (Fosamax), ibandronate (Boniva), risedronate (Actonel or Atelvia), and zoledronic acid (Reclast).
It’s impossible to know whether a drug prevented a fracture in a given individual - you can’t quantify something that never happened - but by comparing large groups of people taking the drug with others who don’t, researchers can estimate how many fractures were averted. Douglas Kiel, director of the Musculoskeletal Research Center at Hebrew SeniorLife’s Institute for Aging Research, says that bisphosphonates as a class have been shown to be effective at preventing fractures. But the data for each drug varies, he says, based on the specific studies that were conducted; the most complete evidence is for Reclast, which has been shown to help prevent several kinds of fractures, including those of the hip and spine.
In the past few years, concerns have emerged over a link between bisphosphonates and a rare type of fracture of the femur in the leg, prompting the FDA to issue a warning on the labels of the drugs. The issue is under investigation, but so far studies suggest the risk is very low. Joel Finkelstein, an endocrinologist at Mass. General, says that concerns shouldn’t lead patients to disregard the well-established benefits of treatment. “Bisphosphonates have been evaluated more thoroughly than most any other medication,’’ he says, and “the evidence for their benefits is far, far greater’’ than the known risks.
Researchers have now been able to look at the safety of taking these drugs for up to 10 years, and Kiel says that they have not found abnormalities in the bone. In light of possible risks, however, physicians are increasingly advising patients to take a drug holiday of a year or two after taking the drugs for long periods of time; because the drugs are deposited in the bone, their effects persist even if treatment is paused.