WASHINGTON -- The maker of the painkiller Darvon is pulling the drug off the market at the request of public health officials who say the more than 50-year-old pill causes potentially deadly heart rhythms. The Food and Drug Administration said Friday that Xanodyne Pharmaceuticals had agreed to halt all U.S. marketing of Darvon and the related brand Darvocet, which have been subject to safety concerns for decades. The Kentucky company confirmed the move in its own statement. The FDA also called on generic drugmakers to stop marketing low-cost drugs containing the active ingredient in Darvon, called propoxyphene. Britain and the...