Originally invented back in 1957, Darvocet is a narcotic painkiller comprised of an opioid similar to codeine called propoxyphene. This opioid has roughly 20% of the potency of morphine and was intended to treat patients for mild to moderate pain. Darvocet was one of the top 25 most prescribed drugs in the history of the United States, being a combination of propoxyphene and acetaminophen, until it was withdrawn from the market in November of 2010. In 2007 alone, more then 20 million prescriptions for propoxyphene-based drugs were written, according to the FDA and possibly as many as 600 million since it’s initial development in 1957. No one can even venture a guess as to how many prescriptions were written for generic counterparts, but the thought is frightening.
Much Ado About Nothing?
But why all the commotion? Why was Darvocet taken off the market in the first place? All it takes is a look at the drug’s track record and the reasons become clear. Darvocet, like most propoxyphene-based products, was easy for the body to build up a tolerance to, so the longer a person took the drug, the less effective it became, requiring the person to take more to get the same desired effect. This cycle created a chemical dependence, or an addiction. In addition to this, the drug caused a number of serious health risks. The first of these goes hand-in-hand with the fast-building tolerance to the drug, as overdoses could occur even at doses only marginally larger than what was prescribed. So patients ran the risk of either overdosing or their medication not being enough to do what was needed. If Darvocet was taken in conjunction with other drugs or alcohol, the result could be a fatal heart attack.
The Public Fights Back
Petitions to remove propoxyphene-based drugs from the market began more than 30 years ago, when the consumer group Public Citizen first petitioned for their removal from the market back in 1978. This petition was suggested on the grounds that propoxyphene was extremely addictive and the ease with which an overdose could occur was troubling. Their request was denied, however, and the Public Citizen group filed another petition in 2006, this time citing the cardiac toxicity associated with the product as the primary concern. Roughly around the same time, studies in Europe were linking propoxyphene to dangerous side effects. One of the most severe side effects found was that these drugs interrupted the electrical activity of the heart, resulting in the United Kingdom banning the drug in 2006. The European Union followed suit and banned the drug in 2008.
In the wake of the bans in Europe, an FDA advisory panel held a vote in 2008 to remove the drugs from the market. While the vote went 14-12, the panel was overturned by FDA regulators instead requested that Xanodyne, the manufacturer of the drug, add warning labels to the medicine’s box. However, the FDA also insisted that Xanodyne perform an in-depth safety study of the drugs in question, which revealed a clear cardiac toxicity upon conclusion of the study. The results of this study prompted the FDA to order the withdrawal of all propoxyphene-based products from the market. This came as no surprise to many physicians, who have called propoxyphene the worst drug in history and responsible for more deaths than any single drug due to it’s extremely addictive nature, poor effectiveness, and toxicity.