Propoxyphene (Darvocet/Darvon)

The Drug

The drug propoxyphene has been used for nearly 50 years to manage moderate pain, and only recently has the safety of the drug come under question.  Like other opiates such as morphine and heroin, propoxyphene produces its pain-reducing effects by activating opioid receptors, and is sold either alone as Darvon, or compounded with acetaminophen as Darvocet.  In recent years, it has been one of the 25 most commonly prescribed medications, with over 22 million people receiving the drug.

According to data at the Federal Drug Abuse Warning Network, deaths linked to Darvocet, Darvon, and generic propoxyphene drugs accounted for over 5% of all drug related deaths between 1987-2006[1].  Expanded, estimates total over 10,000 confirmed deaths, and 2,110 reported accidental deaths associated with the drug since the early 1980s[2].

The Controversy

Since 1978, two citizens’ petitions have been filed requesting the FDA remove the drug from the market due to concerns regarding its safety and effectiveness.  In January of 2009, the FDA held an advisory committee meeting to discuss the safety and efficacy of propoxyphene, ultimately voting 14-12 against removal from the market.  Within the following months, the FDA required the addition of black-box warnings, as well as requiring the manufacturer to conduct a study investigating the cardiac risks associated with propoxyphene use[3].

In November 2010, the FDA again convened to discuss the safety data ordered a year prior.  This time however, the agency moved to ban the drug in response to the new data, stating:

“[T]hese new heart data significantly alter propoxyphene’s risk benefit profile.  The drugs effectiveness in reducing pain is no longer enough to outweigh the drugs serious potential heart risks.”

In their assessment, the FDA noted that a metabolite of the drug, norpropoxyphene, caused significant changes to the electrical activity of the heart.  Even at the recommended dose, negative inotropic effects were observed, weakening the force of muscular contractions in the heart, and potentially resulting in dangerous shifts in normal heartbeat intervals[4].  The FDA further instructed patients how to safely dispose of unused propoxyphene, and advised healthcare professionals to stop prescribing and dispensing the drugs.

Symptoms

Cardiac depression is caused by the cardiotoxic metabolite norpropoxyphene.  Side effects include interruption of the electrical impulses controlling the heart, a slowing heartbeat, and a decreased ability for the heart to contract properly.  These effects can manifest themselves as:

  • Heart arrhythmias
  • Heart attacks
  • Overdose
  • Death

In addition, because the elderly and patients with renal problems have an impaired capacity to clear the cardiotoxic metabolite norpropoxyphene, these populations are especially susceptible to the proarrythmic side effects of the drug.

If you or a loved one have taken Darvocet or Darvon and suffered from any side effects including accidental overdose, intentional overdose, suicide or any form of cardiac emergency, please contact Freese & Goss today. Attorneys are available by phone, e-mail, or by clicking here.

[1] https://dawninfo.samhsa.gov/pubs/

[2] Press Release, FDA Takes Actions on Darvon, Other Pain Medications Containing Propoxyphene, July 7, 2009.

[3] Press Release, FDA Drug Safety Communication: FDA Recommends Against the Continued Use of Propoxyphene, November 19, 2010.

[4] Press Release, FDA Drug Safety Communication: FDA Recommends Against the Continued Use of Propoxyphene, November 19, 2010.

 

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