Researchers Identify Contaminant in Tainted Heparin

-Washington Post

04/24/2008 -- U.S. researchers say they've confirmed that lots of the blood thinner heparin pulled from the market are contaminated with a man-made chemical called oversulfated chondroitin sulfate.

The findings were published online Wednesday inNature Biotechnology.

And, according to a paper published online simultaneously in theNew England Journal of Medicine, the same researchers state that regulators now have at their disposal a test to detect contaminated heparin.

Regulators have said they have been hampered in their efforts to safeguard the public from contaminated heparin because of an uncertainty over exactly what the contaminant is and the lack of a test to spot such a contaminant.

"Sophisticated analytical techniques enabled complete characterization of the contaminant present in heparin. Further, this study also provides the scientific groundwork for critical improvements in screening practices that can now be applied to monitor heparin, thus ensuring patient safety," Ram Sasisekharan, senior author of the papers and the Underwood Prescott Professor of Biological Engineering and Health Sciences and Technology at Massachusetts Institute of Technology, said in a prepared statement.

On Monday, U.S. health officials said they believed that oversulfated chondroitin sulfate (OSCS) might be responsible for the dozens of deaths and hundreds of adverse reactions in the United States that have been linked with contaminated heparin between roughly last November and February.

That belief was bolstered by the fact that the U.S. Food and Drug Administration said it had identified a likely "biological mechanism" by which the oversulfated chondroitin sulfate leads to the adverse reactions seen so far, Dr. Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research, said at a Monday news conference. Those reactions include difficulty breathing, nausea or vomiting, excessive sweating and falling blood pressure, and life-threatening shock.

However, Woodcock added, "it is very important that we all be confident that we understand the link [between the contaminant and reported illnesses], to ensure that the testing that FDA and others have put in place will prevent further adverse events."

U.S. officials also announced Monday that contaminated heparin products have now been found in at least 10 countries, in addition to the United States. The officials also said contaminated lots of the blood thinner have been traced to 12 different Chinese companies that were somehow involved in heparin manufacture.

Woodcock's announcement seemed to conflict with statements made earlier Monday by Chinese health officials who said oversulfated chondroitin sulfate was not responsible for the reported injuries and deaths.

For theNature Biotechnologypaper, researchers from MIT, the FDA, and elsewhere analyzed six heparin preparations that had been linked with adverse reactions in patients, as well as four "control" preparations not associated with adverse events.

All the preparations linked with adverse reactions contained a contaminant similar to chemically synthesized OSCS, the researchers said. According to the FDA, contaminated heparin has now been linked to as many as 81 deaths and hundreds of injuries in United States.

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