Prilosec May Blunt Plavix Benefit

Jan 14, 2008 -- Prilosec and other PPI acid-reducing drugs prevent gastric bleeding in stent patients on Plavix -- but the drugs may block Plavix's lifesaving anticlot action.

This suggestion comes from a small study of 124 heart patients who received stents to open blocked arteries. All of the patients were treated with Plavix to prevent life-threatening blood clots. Half also received Prilosec, a member of the family of powerful acid-reducing drugs called proton pump inhibitors or PPIs. Other PPIs include Nexium, Prevacid, Aciphex, and Protonix.

Researchers Martine Gilard, MD, of Brest University Hospital, Brest, France, and colleagues tested the patients' blood using a measure of clotting activity that is not routinely used in the U.S. They had previously shown that patients whom the test identifies as "poor responders" to Plavix have a significantly higher chance of developing a dangerous blood clot.

After seven days of treatment, Gilard and colleagues found that patients who took Plavix plus Prilosec were more than four times more likely to be "poor responders" to Plavix than were those who received Plavix alone.

"The clinical impact of these results remains uncertain but merits further investigation," Gilard and colleagues conclude.

Because Plavix increases the risk of dangerous bleeding, many doctors routinely give PPIs to patients on Plavix. Gilard and colleagues warn doctors not to do this, and suggest giving PPIs only to patients at high risk of such bleeding.

Gilard and colleagues report their findings in the Jan. 22 issue of the Journal of the American College of Cardiology. An editorial by Paul A. Gurbel, MD, director of the Sinai Center for Thrombosis Research and associate professor of medicine at Johns Hopkins University accompanies the Gilard report.

Gurbel agrees that the Gilard study should stimulate further research, but he strongly argues that the study itself cannot be taken as proof that Prilosec or other PPIs block Plavix.

Why? Gurbel and colleagues have found that different patients have very different responses to Plavix. Blood platelets from some patients, he says, still have very strong clotting ability even though they are taking Plavix.

Because Gilard and colleagues did not test patients for Plavix response before treating them, Gurbel says there is no way to know whether their poor response to the anticlotting drug was a result of PPI treatment.

Nevertheless, Gurbel agrees that doctors should not recommend PPI therapy to stent patients on Plavix unless they have reason to suspect that they are at risk of bleeding.

AstraZeneca, the maker of Prilosec and Nexium, did not reply to WebMD's request for comment in time for publication.