Boston – Two research reports suggest a possible link between two bone-building drugs and irregular heart rhythms in a small number of women who take the medicine.
The signs of a problem were more pronounced with Reclast, a drug made by Novartis AG and given as an annual shot. But there was a hint of similar trouble in a few women who took the leading osteoporosis pill, Fosamax, by Merck & Co. The two drugs are in the same class.
The safety question caught researchers by surprise. While uncertain how big a worry it might be, they agreed the overall risk is small. Specialists said women at high risk for bone breaks – the main target of these osteoporosis drugs – should keep taking them as prescribed.
But several experts said they would be cautious about those who also are at risk for atrial fibrillation, an irregular heart rhythm that can cause strokes.
The two separate reports published in today’s New England Journal of Medicine point to elevated rates of serious episodes of that heart condition in women who took Reclast and Fosamax.
“For the first time, there may be a side effect,” said a researcher involved in both studies, Dr. Steven Cummings of California Pacific Medical Center Research Institute. Until now, people have assumed Fosamax “was completely safe and could be given to almost anybody.”
Fosamax is used by an estimated 1.8 million American women.
Researchers cautioned about overestimating the importance of the heart-rhythm problem. The Reclast study showed little apparent difference in overall cardiac deaths, and the overall risk of the rhythm condition remained small.
Doctors made available by Merck and Novartis said the side effect could be a statistical fluke or just a product of aging.
They said earlier studies showed no sign of the possible side effect.
