Jul. 2, 2009 (United Press International) -- The U.S. Food and Drug Administration announced approval Thursday of Multaq tablets to help maintain normal heart rhythms in patients with heart disorders.

The FDA said Multaq (dronedarone) is designed to treat atrial fibrillation or atrial flutter in patients whose hearts have returned to normal rhythm or who will undergo drug or electric-shock treatment to restore a normal heart beat.

Since Multaq might cause critical adverse reactions, including death, in patients with recent severe heart failure, officials said Multag's drug's label will contain a boxed warning, the FDA's strongest warning, cautioning the drug should not be used by such people.

Multaq is manufactured by the French pharmaceutical company Sanofi-Aventis. (NYSE:SNY)