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.
"Still to be determined is whether or not oversulfated chondroitin sulfate, when combined with heparin, can produce the serious allergic reactions of the sort reported to Baxter and FDA," Woodcock said.
Heparin is often given to dialysis patients and people undergoing heart surgery. The raw materials for the drug come from the mucous lining of pig intestines. Many of those pigs come from rural farms in China, with the intestines often processed by unregulated mom-and-pop workshops before further processing at Scientific Protein's plant in Changzhou.
The reported adverse reactions have included difficulty breathing, nausea or vomiting, excessive sweating and falling blood pressure, which can lead to life-threatening shock.
Since the end of December, there have been 785 reports of allergic reactions associated with Baxter's heparin. This compares with fewer than 100 reports of adverse reactions in all of 2007.
There also have been 46 deaths among heparin users, 19 possibly linked to the drug and four more conclusively so, according to the FDA.
However, since the lots of Baxter's heparin were recalled Feb. 28, no new deaths have been reported, Woodcock said.
Woodcock added that the FDA has been testing imported heparin entering the United States since March 14.
"Doctors and patients now can be confident that the product on the market has been tested and is safe," she said.
For more on heparin, visit the U.S. National Libr
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