The U.S. Court of Appeals for the Third Circuit has rejected arguments that the plaintiffs' claims in the Fosamax litigation should be preempted by U.S. Food and Drug Administration regulations.

The Friday ruling in In re: Fosamax Litigation means that the more than 500 lawsuits targeting Fosamax's manufacturer, Merck & Co. Inc., can proceed after they were initially dismissed at the summary judgment phase. The decision, which the Third Circuit said was a "close call," hinged on whether an informal letter the FDA sent to Merck was sufficient to establish preemption.