Pfizer applies for approval of another Cox-2 inhibitor

Since the recall of Vioxx, all drugs in the Cox-2 inhibitor category have come under intense scrutiny because they all employ the same mechanism to alleviate pain (Related article: Vioxx recall focuses limelight on Cox-2 inhibitor drugs). Apart from Vioxx, which was recalled in September 2004, there are two other drugs still on the market: Celebrex and Bextra (both made by Pfizer). Bextra now carries a strong warning because of cardiovascular risks and serious skin reactions. Similarly, Celebrex has been found to increase the risk of heart attacks.

Another Cox-2 drug, Deramaxx (known generically as deracoxib), that is used as a painkiller for dogs (not approved for human consumption) but works like Vioxx, Celebrex, and Bextra has also come under scrutiny since it has caused deaths of many dogs. This has also focused limelight on another Cox-2 drug Prexige (lumiracoxib) that was meant to be sold as a competitive product to Vioxx but its manufacturer Novartis withdrew the application in Europe after Vioxx was recalled. The application for approval of Prexige has not yet been filed with the FDA. (Related article: Additional evidence found for problems with Prexige)

Now comes the news that, as announced by Pfizer in October 2004, Pfizer has filed an application with the FDA for approval of parecoxib, the injectable version of valdecoxib (Bextra), for treatment of acute pain. It is important to note that while parecoxib is a Cox-2 drug and is no different than Bextra, it is not a conventional painkiller for arthritis. On the other hand, parecoxib is administered intravenously or as a shot into a muscle after surgery.

But not all data about parecoxib is positive. According to the the European Medicines Agency (EMEA) and its Scientific Committee for human medicines, studies showed a higher rate of serious cardiovascular thromboembolic events (e.g. myocardial infarction, cerebrovascular accident) in the parecoxib sodium (Dynastat/Rayzon)/valdecoxib (Bextra) treatment arm compared to the group of patients receiving placebo. This was not observed in a general surgery setting. Accordingly, EMEA has issued warnings on parecoxib and has instructed both doctors and patients to consider the risks of using parecoxib before prescription.

FDA is scheduled to conduct a complete review of the Cox-2 drugs in early 2005 and similar reviews are going on in other parts of the world. There is disagreements among doctors whether all Cox-2 drugs should be recalled till their risk-benefit profiles are better understood, but the world-famous cardiologist Dr. Eric Topol, is not yet convinced that Cox-2 drugs do any more good than an over-the-counter painkiller in most cases.

Related article: FDA limits Celebrex and Bextra use due to Vioxx scare