WASHINGTON — The maker of Darvon and Darvocet announced Friday that it will stop marketing the widely used painkillers in the U.S. because of a new study linking the active ingredient in the drugs to serious and sometimes fatal heart rhythm abnormalities.

Xanodyne Pharmaceuticals Inc., of Newport, Ky., agreed to the ban at the request of the Food and Drug Administration, which also asked makers of generic versions of the drugs' core compound, known as propoxyphene, to stop selling it in the U.S.

The decision to yank propoxyphene brings the U.S. in line with regulatory agencies in Britain and the European Union, which pulled the drug from the market more than a year ago.

Propoxyphene was first approved by the FDA in 1957, but has been shadowed for years by safety concerns.

In January 2009, an FDA advisory committee voted 14-12 against continued marketing of the drug.

The FDA rejected that recommendation, but required a study of the drug's cardiac effects.

The study showed that the drug increases risks for heart arrhythmias even in healthy patients, not just those weakened by illness.

In announcing the withdrawal of the drug, the FDA urged doctors to stop prescribing it immediately. But it advised patients to continue taking propoxyphene, while consulting quickly with doctors to arrange for alternative medication.

The FDA estimated that 10 million patients received propoxyphene in the U.S. in 2009, most of them in combination with acetaminophen, a compound known by the Darvocet trade name.