Recapping the Recall of Darvocet, Darvon
After long standing concerns about the safety of drugs containing propoxyphene, the chief component of Darvon and Darvocet, the FDA finally recalled all propoxyphene-based drugs from US markets late in 2010. These drugs were banned in the UK in 2005 and withdrawn from the European markets in 2009 due to their cardio toxicity and threat to patient safety, leaving many in the US wondering– why the delay?
Longstanding problems with propoxyphene pills
Propoxyphene is the drug marketed as Darvon and, when added with acetaminophen, as Darvocet by Xanodyne Pharmaceuticals Inc. This medication is an opioid, or narcotic, pain reliever prescribed for the treatment of mild to moderate pain. It was first approved by the Food and Drug Administration (FDA) for use in the US in 1957. Though there were concerns of adverse events reported to the FDA throughout the years it was not until the petition filed by Public Citizen, a public interest group, on February 28, 2006 requesting the withdrawal of the drug from US markets that the FDA began to reconsider the drug’s safety.
Public Citizen’s petition for propoxyphene recall
The petition claimed that propoxyphene was a weak analgesic with most of its efficiency coming from acetaminophen when added. The petition also claimed that the drug was particularly cardiotoxic, hindering the heart’s ability to pump blood through the body and causing a variety of heart abnormalities from arrhythmia to heart attack. In addition to the heart problems, the public interest group pointed to an increased suicide rate, accidental death reports, and serious addiction problems linked to the medication. The petition lastly argued that over-prescription and misuse of propoxyphene in the elderly created an increased risk for adverse heart and central nervous system (CNS) reactions. This age group was found to be more susceptible to the drug’s toxicity, even with therapeutic dosing.
FDA rejects 2009 plea to ban Darvocet despite committee agreement
A review was undertaken by experts and a special committee met on January 30, 2009 to discuss the efficiency of propoxyphene and its cardiotoxic potential. The committee voted and by a narrow margin (14 to 12) agreed to discontinue the marketing of the drug in the US. However, on July 7, 2009 after reviewing the petition, data collected, and the committee’s recommendation, the FDA responded that it would not ban Darvocet from market. It instead instituted revisions to the product labeling, developed a Medication Guide, and issued a Public Health Advisory about the drug’s safety concerns. Lastly the FDA required the manufacturer to conduct a clinical trial to assess the potential of the drug to disrupt cardiac conduction or normal heart beats by measuring the effect of dosage on QT prolongation (EKG waves) in normal volunteers.
FDA finally banned Darvocet, Darvon
On August 6, 2009 Public Citizen submitted a new petition asking the agency to reconsider its decision regarding the proposed propoxyphene recall. On November 18, 2010, after the results of the clinical trial and other data were reviewed, the FDA revised its decision and recommended that all drugs containing propoxyphene be withdrawn from the market.
The data from the clinical trial performed by Xanodyne Pharmaceuticals, Inc. showed that the drug was toxic to the heart, both at high doses and at the approved dose. The new information also showed that the risk of a cardiac event could change for an individual at any time during treatment- even after prolonged use. Just a slight change in their metabolic status, other prescription medications, or decrease in kidney function could cause a cardiac arrhythmia to occur.
Propoxyphene pain killers were on the market for over 50 years before the FDA finally banned Darvocet and Darvon.