Osteoporosis Drug May Cause Heart Problems

Osteoporosis is a disease in which bones become fragile and more likely to break. Any bone can be affected, but fractures of the hip and spine are of special concern as they can have serious consequences. A hip fracture usually requires hospitalization and major surgery. It can impair a person’s ability to walk unassisted and may cause prolonged or permanent disability. Spinal or vertebral fracture can cause severe back pain, loss of height and deformity. One class of drugs used to treat osteoporosis is the bisphosphonates, which increases mass to deteriorating bones and reduces the risk of future fractures caused by aging, estrogen deficiency and corticosteroid use. This class of medications includes alendronate (Fosamax), zoledronic acid (Reclast), ibandronate (Boniva), risedronate (Actonel), and others. Although effective, these medications can cause side effects, such as heartburn, abdominal pain, irritation of the esophagus, constipation, and diarrhea. But of more concern are rare side effects which include serious problems with bone healing, particularly after dental surgery, unusual bone fractures, severe or incapacitating bone, joint and muscle pain and most recently—atrial fibrillation (AF), or irregular heartbeat.
For the study, presented at the annual meeting of the American College of Chest Physicians in Philadelphia, researchers analyzed three studies involving more than 16,000 women aged 69 to 75, some of whom took bisphosphonates and some a placebo. Of those who took the drugs, some 2.5 to 3 percent experienced AF, and 1 to 2 percent were hospitalized or died from the irregular heartbeats. Overall, the women taking bisphosphonates were twice as likely to suffer a serious, irregular heartbeat as compared to those taking placebos. “In addition to possible gastrointestinal side effects, bisphosphonates can have possible cardiac side effects. For serious cases of AF, there was a significant increase in risk—about 68 percent,” said review lead author Dr. Jennifer Miranda, an internal medicine resident at Jackson Memorial Hospital in Miami.
AF affects as many as 2.2 million Americans. During AF, the heart’s upper chambers quiver instead of beat, preventing the heart from pumping blood effectively and increasing the risk of blood clots, according to the American Heart Association. If a piece of blood clot leaves the heart and becomes lodged in an artery in the brain, the result is a stroke. An estimated 15 percent of strokes occur in people with AF. “In those patients with a greater risk factor for AF, health care professionals should cautiously choose osteoporosis treatment and consider the potential risks versus the benefits carefully,” Miranda said in a news release.
These new findings add to previous warnings about the medicines. A study and editorial published in the May 3, 2007 issue of the New England Journal of Medicine (NEJM) found that, while the drugs reduced the risk of fractures, it increased the incidence of AF in women getting a once-yearly infusion of bisphosphonates. In October 2007, the U.S. Food and Drug Administration said it would continue to investigate the connection, but did not recommend a change in prescribing patterns.
A spokesman for Merck, the maker of Fosomax, said the company “looks forward to reviewing” the study findings and referred to a statement on Merck’s Web site released after the NEJM data was published suggesting that “an association between AF and treatment with Fosomax was very unlikely.” And in a statement, manufacturer Novartis said, “We are confident about the safety profile of Reclast.” It said that only the NEJM study had shown an increased rate of AF among patients taking the drug, and “90 percent of those events occurred more than one month after the infusion, suggesting that AF was not related to the infusion.”
But researchers at the conference urged continued studies. “Bisphosphonates are widely used to treat millions of women and men who suffer from osteoporosis or low bone density,” said James A. L. Mathers, Jr., president of the American College of Chest Physicians. “A potential link between bisphosphonates and AF warrants additional research in this area.”