Study eyes mechanisms to blame for Vioxx risks

A new study purports to explain how and why Cox-2 inhibitors increase the risk of heart problems. Researchers found that blocking the Cox-2 enzyme, which relieves pain without the stomach problems associated with other meds, has some unintended consequences.

A cascade of them, in fact, the University of Pennsylvania's Garret FitzGerald told The Wall Street Journal Health Blog. Based on data from a study in genetically modified mice, researchers concluded that one of the fats made by the Cox-2 enzyme protects the heart. In addition, blocking Cox-2 suppresses production of other heart-protecting molecules, the Science Translational Medicine study showed.

Cox-2 inhibitors include, of course, the now-withdrawn (and infamous) Vioxx. Pfizer's ($PFE) Celebrex is the only Cox-2 drug still on the market, and its label warns of the cardiovascular risks. Merck ($MRK) told the Health Blog  it hadn't fully reviewed the latest study, but "animal studies do not always translate well into humans." For its part, Pfizer said the mouse study doesn't offer enough evidence to support conclusions about Celebrex's benefits and risks. The company is conducting a trial looking at the drug's long-term safety risks.

- read the Health Blog post