On Monday US regulators ordered Sanofi, the French pharmaceutical giant, to change the label of its heart drug Multaq after it was found to double the risk of death in certain patients.
Patients with permanent abnormal heart rhythm, or atrial fibrillation, should not take the drug -- also known as dronedarone -- because of a two-fold higher rate of cardiovascular death, stroke, and heart failure, the US Food and Drug Administration said.
The change is based on results of a clinical trial of the drug in patients with permanent atrial fibrillation that was halted early, in July, due to the increased risk of adverse events.
However, another clinical trial in patients with a different type of heart flutter, known as non-permanent atrial fibrillation, has shown the drug "provides a benefit," and may continue to be prescribed, the FDA said.
Since the FDA approved the drug in July 2009, 1.3 million prescriptions have been dispensed in the United States, US regulators said.