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Bisphosphonates not linked to atrial fib, FDA review finds.

A Food and Drug Administration safety review of bisphosphonates has not found a clear association between bisphosphonate therapy and atrial fibrillation, the agency announced.

"Based on the data available at this time, health care professionals should not alter their prescribing patterns for bisphosphonates and patients should not Stop taking their bisphosohonate medication," the FDA said in a statement on its MedWatch Web site.

The review compared data on 19,687 patients treated with a bisphosphonate and 18,358 patients who received placebo: follow-up ranged from 6 months to 3 years.

Four bisphosphonate manufacturers provided the data in response to the FDA's request in October 2007, after concerns were raised about a possible association between bisphosphonates and an increased risk for serious atrial fibrillation in a study and related comment published in the May 3, 2007, issue of the New England Journal of Medicine (2007:356:1809-22; 1895-6).

The manufacturers of alendronate (Fosamax and Fosamax plus D, by Merck & Co.), ibandronate (Boniva, by Roche Laboratories), risedronate (Actonel and Actonel with calcium, by Procter & Gamble Pharmaceuticals), and zoledronic acid (Reclast and Zometa, by Novartis) included data from men and women treated with each of those drugs. The review of these data found that cases of atrial fibrillation were "rare," with two or fewer cases reported in most of the studies. The absolute difference in rates of atrial fibrillation between each bisphosphonate and placebo arm ranged from zero to 3 cases/1,000 people, according to the FDA.

In a large zoledronic acid study, the rate of serious atrial fibrillation was significantly higher in treated patients. But "across all studies, no clear association between overall bisphosphonate exposure and rate of serious or nonserious atrial fibrillation was observed," the FDA said. In addition, increasing the dose or duration of treatment was not associated with an increased rate of atrial fibrillation. (The label for zoledronic acid, which is administered intravenously once a year for osteoporosis, does include information about increased risk for serious atrial fibrillation.

The statement says that the agency is aware of "discordant results" from the literature and epidemiologic studies regarding the incidence and clinical course of atrial fibrillation in patients taking bisphosphonates and is "exploring the feasibility of conducting additional epidemiologic studies to examine this issue."

The FDA also continues to monitor postmarketing reports of atrial fibrillation in people treated with bisphosphonates, which are approved for treating osteoporosis, Paget disease, and some cancer-related indications.

In the 2007 studies, 1.3% of the women on Reclast and 1.5% of those on Fosamax developed serious atrial fibrillation (defined as life-threatening cases and/or those resulting in hospitalization), compared with 0.5% and 1.0%, respectively, with placebo. For serious and nonserious cases of atrial fibrillation combined, the rates were not significantly different in the treatment and placebo groups. The patients were women aged 65-89 years with osteoporosis.

Bisphosphonate products approved by the FDA but not included in the safety review are etidronate (Didronel, by Procter & Gamble Pharmaceuticals), pamidronate (Aredia, by Novartis), and tiludronate (Skelid, by SanofiAventis US).

The FDA statement can be found at Serious or unexpected adverse events associated with bisphosphonates can be reported to the FDA's MedWatch program at 800-332-1088 or


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Author:Mechcatie, Elizabeth
Publication:OB GYN News
Date:Nov 15, 2008
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