Raw heparin is derived from pig intestines, and it's often processed by small, unregistered mom-and-pop workshops in China. Heparin is used for certain types of surgery to prevent blood clots. Kidney patients also take it before undergoing dialysis.
Oversulfated condroitin sulfate mimics heparin's qualities and is a modified form of chondroitin sulfate. Condroitin 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.
"The fact that we have established a mechanism by which this [oversulfated condroitin sulfate] might cause adverse events we think strengthens the association considerably," Woodcock said. "In the test tube, if we use heparin with OSCS, we see changes in blood mediators that could lead to this reaction. In addition, this has been observed in animals, and we just heard today from another group of experts that they have also observed this so we think this story is starting to come together."
For now, however, the U.S. heparin supply seems to be safe, she said.
"The heparin supply in the U.S. is tested and is free of this contaminant," Woodcock said. "We now feel that we have a mechanistic link so we feel that testing requirements put into place will prevent reoccurrence of this event."
The U.S. National Library of Medicine has more on heparin.
SOURCES: April 21, 2008, news conference with Janet Woodcock, M.D., director, Center for Drug Evaluation and Research, U.S. Food and Drug Administration; April 21, 2008, prepared statement, Scientific Protei
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