FDA Warns Plavix Patients of Drug Interactions
Plavix Dulled by Nexium, Prilosec, Tagamet, Prozac, Other Drugs
WebMD News Archive
Nov. 17, 2009 - The FDA today warned patients not to combine Plavix
with Nexium, Prilosec, and nine other drugs -- including Prozac and
The drugs may make the anti-clotting drug Plavix dangerously less
effective, the FDA says. They block an enzyme in the body that turns the
drug into its active form. Plavix is the second most-prescribed drug in the
not the first time questions have been raised about the
potent stomach-acid-reducing drug
Prilosec blunting the benefit of Plavix. But data from more recent studies
suggested that Prilosec -- and a similar drug called Nexium --
might actually help patients on Plavix.
This led the FDA to ask Plavix maker Sanofi-Aventis to specifically study
interactions between Plavix and Prilosec and between Plavix and Nexium, FDA
safety evaluator Mary Ross Southworth, PharmD, said at a news conference.
"We think there is a significant interaction," Southworth said. "In general,
patients should avoid the combination of these two medications."
But the FDA recommendation goes far beyond the two drugs studied. Nexium and
Prilosec interfere with Plavix not because they are members of a particularly
powerful class of acid-reducing drugs called proton pump inhibitors or PPIs,
but because they inhibit an enzyme, CYP 2C19, that activates Plavix.
Several other drugs also inhibit CYP 2C19, and the FDA says patients on
Plavix should avoid them as well. These drugs are:
Patients taking Plavix should not stop taking any of these drugs --
including Nexium and Prilosec -- until speaking with a doctor. It's dangerous
to stop taking any medication without medical advice.
Patients taking Plavix should call their doctor as soon as possible to
discuss all the other drugs and supplements they are taking, including over-the-counter
The FDA warning does not cover other acid-reducing drugs except for Tagamet,
which inhibits CYP 2C19. The FDA is actively looking at data on other PPIs, but
at this time the FDA is not warning patients to avoid taking Plavix along with
The FDA says there's no evidence that the acid reducers Zantac, Pepcid,
or Axid interfere with Plavix.
While some doctors have tried to avoid drug interactions by having patients
take Nexium or Prilosec 12 hours before or after taking other drugs, the FDA
says this strategy will not avoid interactions between Nexium or Prilosec and