Experts don't expect to see genetic testing become standard procedure for patients taking the blood-thinner Plavix.
The Food and Drug Administration is adding its strongest black-box warning to the label, saying that some patients don't respond to the drug.
The agency said patients with a genetic variation can't metabolize it. And it says that puts them at increased risk for heart attack and stroke.
Patients can determine if they are "poor metabolizers" by taking a genetic test. The FDA recommends that these patients use other blood thinners, like aspirin.
But genetic tests cost around $500. And a New Jersey cardiologist, Dr. Louis Teichholz, says it's "premature to say that everyone who gets Plavix needs to be tested."
He said the black-box warning could push more doctors to prescribe Effient, a competing blood thinner launched last summer by Eli Lilly.
