Two new research reports suggest a link between some bone-building drugs and irregular heart rhythms in a small number of women who use them. The problem is most pronounced with Reclast, a drug given through a once-a-year, 15-minute intravenous infusion. But researchers also focused on similar problems in women taking the leading osteoporosis pill, Fosamax, leading experts to express cautions about giving the drugs to those who also are at risk for a condition called atrial fibrillation, an irregular heart rhythm that can cause strokes.
The two separate reports, published in the May 3, 2007 issue of the New England Journal of Medicine (NEJM) point to elevated rates of serious episodes of atrial fibrillation in women who took either Reclast or Fosamax.
“For the first time, there may be a side effect,” said a researcher involved in both studies, Dr. Steven Cummings of the California Pacific Medical Center Research Institute. Until now, people have assumed Fosamax “was completely safe and could be given to almost anybody.”
There appeared to be 50 percent more risk of the serious heart rhythm in women who took the daily pill than among those who didn’t take it. About half of the 6,459 women took Fosamax; of these 47 developed atrial fibrillation, compared with just 31 cases among the other women.
While the finding is not statistically definitive for Fosamax, the numbers worried some researchers because it is in line with the results of a new study published in the same issue of the medical journal.
That study of 7,736 postmenopausal women with bone-thinning osteoporosis focuses on Reclast, known generically as zoledronic acid. Currently approved for Paget’s disease, another bone condition, the manufacturer, Novartis AG, hopes to get approval later this year to sell it for osteoporosis use. The new study, financed by Novartis, shows that Reclast works at least as well as existing drugs in the same class, researchers say. However, the risk of a serious case of irregular heart rhythm was more than double that in the other patients – 50 cases in the drug-taking half, compared with 20 cases in the others.
1. Juliet Compston, M.D., F.R.C.P., F.R.C.Path., F.Med.Sci. Treatments for Osteoporosis – Looking beyond the HORIZON. NEJM, Vol. 356:1878-1880, May 3, 2007, Number 18.
2. Dennis M. Black, Ph.D., Pierre D. Delmas, M.D., Ph.D., Richard Eastell, M.D, et al. Once-Yearly Zoledronic Acid for Treatment of Postmenopausal Osteoporosis. NEJM, Vol. 356:1809-1822, May 3, 2007, Number 18.