Test helps determine if Plavix is working
Posted April 19, 2010
Raleigh, N.C. — A year and a half ago, Albert Freund was on his way to work and began feeling a slight pain in his chest, which grew worse.
“I broke out into a sweat and the pain got real stiff in my arm,” he said.
Freund, 69, was having a heart attack.
Doctors ended up placing a stent in Freund to open a blocked artery in his heart. He was also prescribed the blood thinner Plavix to prevent clots. The U.S. Food and Drug Administration recently placed a black box warning on Plavix because some patients cannot metabolize the drug, placing them at a higher risk of a heart attack or stroke.
Until recently, Freund hasn't known if Plavix is working for him.
“There are some people, because of specific genes that they carry, that don't turn Plavix into its active form,” said Dr. Cam Patterson, chief of cardiology at UNC Hospitals.
“If we can identify those patients early, we can make important decisions for them that are going to impact the therapy they're going to receive for a long period of time,” UNC cardiologist Dr. Joseph Rossi said.
UNC researchers developed testing to detect the genetic markers for the 2 to 4 percent of patients who don't respond to Plavix or others who are poor or intermediate responders.
A current study tests all UNC patients prescribed the drug. It's a simple blood test with results in one to two days.
Doctors found Plavix was working for Freund. If the drug wasn’t, Rossi could have prescribed a newer blood thinner called Prasugrel.
“The disadvantage is that it (Prasugrel) is more expensive. It does cause more bleeding side-effects,” Patterson said.
In the study, poor responders, about 34 percent of patients, may get double doses of Plavix or they may be prescribed Prasugrel.