FDA Identifies Contaminant in Blood-Thinning Drug

By Steven Reinberg
HealthDay Reporter
Thursday, March 20, 2008; 4:00 AM

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WEDNESDAY, March 19 (HealthDay News) -- U.S. health officials say they've identified the contaminant found in the blood-thinner heparin, which has been linked to hundreds of allergic reactions and possibly 19 deaths in the United States.

The contaminant is a man-made chemical called oversulfated condroitin sulfate, but U.S. Food and Drug Administration officials could not say Wednesday how it got into the heparin. And they're not even sure it's to blame for the allergic reactions and deaths.

But Dr. Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research, said the oversulfated condroitin sulfate was the only contaminant found in samples of the blood thinner, which was produced in China for Baxter Healthcare Corp., based in Deerfield, Ill.

Oversulfated chondroitin sulfate mimics heparin's qualities and is a modified form of chondroitin sulfate. Chondroitin sulfate is a naturally occurring substance made from animal cartilage and is often used in supplements to treat arthritic joints. But, oversulfated chondroitin sulfate is man-made and doesn't occur naturally.

"It is most likely that chondroitin sulfate was chemically modified to create this compound," Woodcock said during a teleconference. "Oversulfated chondroitin sulfate, unlike common chondroitin sulfate, mimics heparin's activity, therefore appears to be heparin when subjected to standard tests."

The contaminant was found in samples of heparin that the FDA tested from Scientific Protein's Changzhou SPL plant in China, which supplied Baxter with the active ingredient in heparin, Woodcock said. It was also found in Baxter's heparin products in the United States, she said.

"Testing of these samples suggests that the contaminant accounted for approximately 2 to 50 percent of the total content of the active pharmaceutical ingredient in some of these samples," Woodcock said.

Woodcock said that the FDA doesn't know if the contaminant wound up in the heparin deliberately or by accident, and that the agency was trying to answer that question. But, she noted that oversulfated chondroitin sulfate is less expensive than the active pharmaceutical ingredient in heparin.