On August 27, 2007, the Journal of Experimental Medicine published a study that may have found the cause of dangerous heart problems in patients who take pain medications like Vioxx.

A group of scientists, led by Mallika Ghosh at the University of Connecticut, found through experiments with mice that when cox-2 inhibitors like Vioxx block the cox-2 enzyme, they reduce pain while at the same time increase the production of a protein called tissue factor (TF). TF can initiate unwanted blood clotting, which could lead to a heart attack or stroke.

Prior to the study, the increased heart risk was attributed to prostacyclin, a protein whose levels are lowered by cox-2 inhibitors. Prostacyclin, however, helps prevent blood clotting.

Ghosh also believes the risk from the production of TF levels applies to all cox-2 inhibitors, not just Vioxx. Other cox-2 inhibitors include Bextra and Celebrex. Vioxx was pulled from the market in 2004, and Bextra in 2005, because of heart-related risks. Celebrex remains on the market.

This new study may mean cox-2 inhibitors can be made safer for patients by introducing TF-blocking drugs along with the pain killers. However, Dr. Steve E. Nissen, chairman of the department of cardiovascular medicine at the Cleveland Clinic, said this theory is speculative.

“The problem is that there are no approved TF-blockers, so it’s not even feasible to consider this,” Nissen said.

Source: Steven Reinberg, “Study points to cause of Vioxx heart risk,” HealthDay News, August 27, 2007.