The painkillers Darvon and Darvocet have a long and controversial history that has propelled them into the mainstream news following their recall on November 19, 2010.
Invented in 1957 by Eli Lilly & Co., Darvon and Darvocet are comprised of an opiate called propoxyphene. An opiod similar to codeine, propoxyphene simulates 20 percent of the effect of morphine and was intended for the treatment of mild to moderate pain. When mixed with acetaminophen, propoxyphene was sold as Darvocet, one of the top 25 most-prescribed drugs in United States history before its withdrawal from the marketplace.
According to the FDA more than 20 million prescriptions were written for propoxyphene-based products in 2007 alone and as many as 600 million may have been written since 1957. Countless similar prescriptions were also given for its generic counterpart.
Millions of chronic pain suffers found relief using Darvon and Darvocet produced by Xanodyne Pharmaceuticals along with their generic versions distributed by Qualitest and Vintage Pharmaceuticals. Unfortunately for patients prescribed propoxyphene based drugs, the pain killers cause a number of serious adverse health effects.
Long time users have been found to build a tolerance to propoxyphene, which has led patients to increase their administered dosage of the painkillers. Overdoses occur at even marginally larger doses than those prescribed by a physician and if taken in concert with other drugs or alcohol may cause a fatal heart attack.
For the past 30 years, consumer groups have been petitioning for the removal of propoxyphene-based pain killers from the marketplace. In 1978, the consumer group Public Citizen first suggested removal of propoxyphene from the marketplace due to its addictive properties and the ease with which overdoses occurred. With its request denied, it filed a second petition in 2006, citing the concern for cardiac toxicity associated with the drugs.
Research in Europe also linked dangerous side effects to the drugs. European research showed that the drugs interrupt the electrical activity of the heart, leading the United Kingdom to ban propoxyphene in 2006. The European Union followed with its own ban in 2008.
An FDA advisory panel voted 14-12 to withdraw the drugs from the marketplace in 2008. Regulators at the FDA overruled the panel, instead, requesting that Xanodyne add warning labels to the box the medicines were sold in. The FDA also asked Xanodyne to conduct an in-depth safety study of the medications in question. Upon the study's conclusion, the medications showed a clear cardiac toxicity prompting the FDA to withdraw of all propoxyphene-based drugs from the market.
More than 30 years and 600 million prescriptions later, Public Citizen is calling for a Congressional inquiry into the FDA's handling of the matter, which has left millions with negative side effects and cardiac problems.