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.

Related Stories

FDA warning: some patients cannot process Plavix

date 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

date 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

date 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

Teva to lift bid for Mylan: report

date 3 hours ago

Israeli pharmaceutical giant Teva plans to increase its bid for rival Mylan and could announce the move as soon as this week, according to a US media report Monday.

Vaccine for West Nile Virus enters human clinical trials

date 8 hours ago

A clinical trial of a new investigational vaccine designed to protect against West Nile Virus infection will be sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes ...

FDA clears drug for leading form of cystic fibrosis

date Jul 02, 2015

Federal health officials have approved a new combination drug for the most common form of cystic fibrosis, the debilitating inherited disease that causes internal mucus buildup, lung infections and early death. But it will ...

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.