Propoxyphene Withdrawn: What Could Be Next?
Hi. My name is Dr. Charles Argoff, Professor of Neurology at Albany Medical College and Director of the Comprehensive Pain Center at Albany Medical Center in Albany, New York. What I'd like to talk about today is the recent FDA action, which resulted in the removal of propoxyphene-containing products from the US market. These would be brand name products like Darvon and Darvocet. I say "from the US market" because many of you may know that, in fact, that the United States was not the first country to remove propoxyphene from its market. The United Kingdom removed propoxyphene from its market in 2005. On several occasions the FDA advisory committees have actually recommended to the FDA that propoxyphene-containing products be removed from the market, but the FDA did not heed their advice until recently.

Why was it removed? The official reason is the concern about cardiovascular (arrhythmia producing) side effects. With concern about cardiac safety issues, the companies that manufactured Darvocet and Darvon were asked to do a safety study in which the risk for arrhythmia was analyzed. This was seen to be too high, but I'd like to go beyond that. For many years it has been known that propoxyphene-containing products, such as Darvocet (in one Canadian study that was done over a decade ago) do not provide any more pain relief than aminophen or aspirin alone.

It perplexed a number of us for many years that individuals were prescribed propoxyphene-containing products when these drugs didn't appear to provide any greater pain relief than more simple approaches. Now that's just part one of what I'd like to say in this segment of my discussion. However, lurking out there, so to speak, is another issue. Several years ago, Europe's equivalent of the Drug Enforcement Agency, the European Medicines Agency (EMEA), received information from Norway about the use of Soma (carisoprodol) as a muscle relaxant and concerns about its ability to create dependency. In fact, Sweden and Norway have removed Soma from their markets, and the EMEA has advised all its member nations to actually remove the drug from their markets.

Nevertheless, this is a medication that's still sold in the United States as a muscle relaxant. The reason that I bring it up is that Soma has its own set of issues that we all should be concerned about, much like some of the issues associated with Darvon. Soma was actually manufactured originally and created to be chemically similar to a sleep aid that's not used as much anymore -- meprobamate. In the 1950s and 1960s and even until the 1970s, meprobamate was known as Miltown and was one of the more commonly misused sleep agents. A lot of issues of misuse arose with that particular drug.

So I caution those of you who use Soma for your patients as a muscle relaxant that it is metabolized to meprobamate, which, in fact, is an agent that has significant issues and a long history with respect to misuse. I also caution you that like Darvon and Darvocet, which for many years have been off the market in at least 1 other country, Soma has been taken off the market in countries outside the United States. When we prescribe, it's important to think about what we can prescribe that will help our patients, but in the safest manner possible. Thank you.