Genetic test for Plavix use may be unneeded: study

A new study published Wednesday cast doubt on the usefulness of a genetic test for patients taking the anti-coagulant drug Plavix, calling into question last year's FDA warning about the blood thinner.

The study, a new review of 32 previous clinical studies published in the , said the genetic test may not help identify those patients more at risk of a heart attack or other cardiac event.

Plavix, one of the world's top selling drugs, is marketed by US-based Bristol-Myers Squibb and France's Sanofi. It reduces the risk of heart attack and stroke by keeping from sticking together to cause clots.

In 2010, the US Food and Drug Administraion ordered the manufacturers to add a boxed warning to Plavix packets saying the drug may be less effective in preventing heart attacks in people who cannot metabolize it properly.

The FDA said an estimated two to 14 percent of the US population are poor metabolizers who have a certain variant of the gene that makes the CYP2C19 , which converts Plavix to its active form.

The FDA had recommended that doctors prescribe higher doses of Plavix, or clopidogrel, to those patients who had the genetic test and were found not to produce enough of the enzyme.

But researchers led by Michael Holmes at University College London concluded after their new review of studies involving 42,000 patients that those with the did not have more than other patients.

"Despite associations between CYP2C19 genotype, clopidogrel metabolism, and platelet aggregation, this systematic review and meta-analysis does not demonstrate a clinically important association of genotype with ," researchers led by Michael Holmes at University College London said.

The only notable possible exception was in patients with stent thrombosis, they wrote.

"The FDA's warnings on Plavix were premature and were not based on solid science," said Steven Nissen, a cardiologist at the Cleveland Clinic Foundation, in an editorial published in the Journal of the AMA.

Plavix sales totalled $5.4 billion in the first three quarters of 2011, as compared with $4.9 billion in the same period last year.

About 40 million people take the drug worldwide.

add to favorites email to friend print save as pdf

Related Stories

FDA warning: some patients cannot process Plavix

Mar 12, 2010

(AP) -- The Food and Drug Administration is adding its strongest warning to the label for Plavix, cautioning that some patients do not respond to the blockbuster blood thinner.

FDA says heartburn drugs can interfere with Plavix

Nov 17, 2009

(AP) -- Federal health officials said Tuesday a popular variety of heartburn medications can interfere with the blood thinner Plavix, a drug taken by millions of Americans to reduce risks of heart attack ...

FDA clears Eli Lilly's blood thinner Effient

Jul 10, 2009

(AP) -- The Food and Drug Administration on Friday approved a highly anticipated blood thinner from Eli Lilly, though the drug must carry the agency's sternest warning because of its bleeding risks.

Recommended for you

FDA OKs Cubist antibiotic for serious infections

Dec 20, 2014

The Food and Drug Administration has approved a new medicine to fight complex infections in the abdomen and urinary tract, the fourth antibiotic the agency has approved since May.

Xtoro approved for swimmer's ear

Dec 18, 2014

(HealthDay)—Xtoro (finafloxacin otic suspension) eardrops have been approved by the U.S. Food and Drug Administration to treat swimmer's ear, clinically known as acute otitis externa.

Drug interaction identified for ondansetron, tramadol

Dec 18, 2014

(HealthDay)—In the early postoperative period, ondansetron is associated with increased requirements for tramadol consumption, according to a review and meta-analysis published online Dec. 10 in Anaesthesia.

New system targets germs in donated blood plasma

Dec 17, 2014

(HealthDay)—A new system designed to eliminate germs in donated blood plasma and reduce the risk of transmitting a plasma-borne infection has been approved by the U.S. Food and Drug Administration.

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.