Prilosec May Blunt Plavix Benefit
PPI Acid-Reducing Drugs May Block Anticlot Medicine Needed by Stent Patients
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
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
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.