Heparin Contaminant Identified

After weeks of questions and few answers, FDA has identified the contaminant in batches of Baxter’s blood-thinner heparin as over-sulfated chondroitin sulfate, a modified version of a biologically derived compound not found in heparin.

The over-sulfated compound found in the batches is unnatural and is more than likely chemically modified, Janet Woodcock, director of FDA’s Center for Drug Evaluation and Research, told press this morning. However, the modified compound mimics heparin’s activities and appears to be heparin when subjected to standard tests.

“It is still to be determined if this compound, when combined with heparin, can produce the allergic reactions reported to Baxter and FDA,” Woodcock continued.

The sulfate was found in batches of heparin manufactured at the Changzhou SPL plant in China, Baxter’s API supplier and ground zero for many of the tainted lots. Over-sulfated chondroitin sulfate is not approved in the United States and shouldn’t be present in heparin, Woodcock said.

Over-sulfated chondroitin sulfate is not a compound that naturally occurs in heparin and is not something that would be purified away during processing. FDA does not know if the contaminant was introduced accidentally or on purpose and is not ruling out counterfeiting.

Unmodified chondroitin sulfate is traditionally used as a dietary supplement and is derived from animal cartilage. The over-sulfated version found in the tainted batches of heparin could only be chemically created.

“It didn’t come straight from the pig—that would be improbable,” one FDA official told the press. “We do not know why or how it was introduced.”

There have been no additional allergic reactions reported since Baxter widened its recall of heparin in February. To date, there have been 19 deaths attributed to allergic reactions stemming from use of heparin.