The maker of Darvon and Darvocet announced Friday that it would stop marketing the widely used painkillers in the U.S. because a new study links the active ingredient to serious and sometimes fatal heart rhythm abnormalities.
The FDA requested the withdrawal and urged doctors to stop prescribing the drugs immediately. But it advised patients to keep taking their medication while consulting quickly with physicians to find an alternative. Pain management experts said the drugs are easily replaceable.
The decision follows years of controversy about Darvon's dangerous side effects.
Sidney Wolfe of Public Citizen's Health Research Group blasted the FDA's action as too late and called for congressional hearings into why the agency took so long. Public Citizen tried for more than three decades to limit use of the drug and petitioned the FDA to ban it in 2006.
Known generically as propoxyphene, Darvon is an opioid used to treat mild to moderate pain. Made by Xanodyne Pharmaceuticals Inc. of Newport, Ky., the drug was approved by regulators in 1957. Less than 1% of prescriptions are for the brand name, the company said. The FDA also asked generic manufacturers to stop making it for the U.S. market.
The FDA estimated that propoxyphene was used by 10 million people in 2009, with most of them receiving it in combination with acetaminophen, a compound known by the trade name Darvocet.
Many doctors who prescribe propoxyphene do so simply because it's been around so long and they're familiar with it, said Al Anderson, a Minneapolis family practitioner and president of the American Academy of Pain Management board of directors.
Anderson said the withdrawal would hurt a few patients who can't tolerate other painkillers, but most patients have many alternatives, such as oxycodone, morphine and Nucynta.
"It certainly takes one tool away, but it's a small tool," Anderson said.
"We have many better options," said Mehul Desai, director of pain medicine at George Washington University Hospital in Washington. "It tends to be a pretty poor pain reliever."
Propoxyphene was effectively pulled from the British and European Union markets earlier because of regulators' health concerns: Britain in 2005 and the EU in June 2009.
In January 2009, an FDA advisory committee voted 14-12 against continued marketing of propoxyphene. The FDA rejected that recommendation but required a study of the drug's cardiac effects.
That study showed an increased risk for heart arrhythmias even in healthy patients, not just those weakened by illness.
"We concluded that the pain-relief benefit no longer outweighed the health risks," said John Jenkins, director of new drugs in the FDA's Center for Drug Evaluation and Research, in a telephone news conference with reporters.
Wolfe said the FDA should have acted much sooner. Data about heart toxicity was available from an animal study 30 years ago, he said, and at least 1,000 people in the U.S. have died from using propoxyphene since Britain's 2005 ban.
He labeled the agency's inaction "a serious indictment of the FDA's long-lasting unwillingness to protect people in this country from a deadly but barely effective painkiller."
But judged against its regulatory behavior in recent years, Friday's announcement continues a harder line on drug safety. It's the second time in six weeks the FDA has pushed to have a drug removed from the market.