The agency made this declaration after reviewing trial data from four drugmakers - Merck’s Fosamax; Roche’s Boniva; Novartis’ Reclast and Zometa, and Procter & Gamble’s Actonel. In a statement on its web site, the FDA found the risk of atrial fibrillation was “rare within each study, with most studies containing two or fewer events.”

Just the same, the FDA noted conflicting findings in other studies and may consider epidemiologic studies to further investigate any risks with the drugs, which are known as bisphosphonates. The agency began examining concerns in women taking the drugs in October 2007 following reports of serious problems cited in The New England Journal of Medicine five months earlier (see here).

Since then, the FDA collected data on nearly 40,000 patients - 19,687 given a bone drug and 18,358 given a placebo - who were studied in clinical trials between six months and three years. The occurrence of atrial fibrillation was rare within each study, with most studies containing 2 or fewer events. The absolute difference in event rates between each of the bisphosphonate and placebo arms varied from 0-3 per 1,000, according to the FDA.

“Across all studies, no clear association between overall bisphosphonate exposure and the rate of serious or non-serious atrial fibrillation was observed. Increasing dose or duration of bisphosphonate therapy was also not associated with an increased rate of atrial fibrillation,” the FDA wrote. Meanwhile, here is a statement from Merck.