The painkillers Darvon and Darvocet (propoxyphene) are being pulled from the market today because of their association with serious or even fatal heart rhythm abnormalities. The US Food & Drug Administration (FDA) is also asking the manufacturers of generic propoxyphene-containing products to remove those products from the market.
Darvon and Darvocet are both made by Xanodyne Pharmaceuticals Inc. Propoxyphene is an opioid used to treat mild to moderate pain. First approved by the FDA in 1957, propoxophene is sold by prescription under various names both alone (e.g., Darvon) or in combination with acetaminophen (e.g., Darvocet).
Since 1978, the FDA has received two requests to remove propoxyphene from the market. Until now, the FDA had concluded that the benefits of propoxyphene for pain relief at recommended doses outweighed the safety risks of the drug.
In January 2009, the FDA held an advisory committee meeting to address the efficacy and safety of propoxyphene. After considering the data submitted with the original drug applications for propoxyphene, as well as subsequent medical literature and postmarketing safety databases, the committee voted 14 to 12 against the continued marketing of propoxyphene products. In making this recommendation, the committee noted that additional information about the drug’s cardiac effects would be relevant in weighing its risks and benefits.
In July 2009, the FDA decided to permit continued marketing, but required that a new boxed warning be added to the drug label alerting patients and health care professionals to the risk of a fatal overdose. In addition, the agency required Xanodyne to conduct a new safety study assessing unanswered questions about the effects of propoxyphene on the heart.
The agency has since has reviewed the data from that study, which show that, even when taken at recommended doses, propoxyphene causes significant changes to the electrical activity of the heart. These changes, which can be seen on an electrocardiogram (ECG), can increase the risk for serious abnormal heart rhythms that have been linked to serious adverse effects, including sudden death, the FDA said.
The available data also indicate that the risk of adverse events for any particular patient (even patients who have taken the drug for many years) is subject to change based on small changes in the health status of the patient, such as dehydration, a change in medications, or decreased kidney function, the agency said. As a result of these data, combined with other information, including new epidemiological data, the agency concluded that the risks of the medication outweigh the benefits.
“With the new study results, for the first time we now have data showing that the standard therapeutic dose of propoxyphene can be harmful to the heart,” said Gerald Dal Pan, M.D., M.H.S., director of the Office of Surveillance and Epidemiology in the FDA’s Center for Drug Evaluation and Research.. “However, long-time users of the drug need to know that these changes to the heart’s electrical activity are not cumulative. Once patients stop taking propoxyphene, the risk will go away.”
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