The contaminant found in samples of heparin that had been linked to an increase in adverse reactions has now been identified as oversulfated chondroitin sulfate.
In a telephone press conference, Dr Janet Woodcock (director of the FDA Center for Drug Evaluation and Research) explained that chondroitin sulfate was derived from animal cartilage and was used as health supplement, but the oversulfated version did not occur naturally and would have to have been chemically synthesized, probably by simply adding extra sulfate molecules to chondroitin sulfate, which is extensively available. "We do not know how this substance got into the heparin supply, but we can say it did not come straight from the pig," she said.
The oversulfated chondroitin sulfate is very closely chemically related to heparin and appears to be heparin in standard tests, Woodcock noted. The contaminant was found to make up 2% to 50% of the total content of heparin active pharmaceutical ingredient in some of the samples tested at the Changzhaou SPL plant in China to which it has been traced, she added.
Woodcock and other FDA officials said that oversulfated chondroitin sulfate would be cheaper to produce than heparin itself but would not be drawn in on suggestions that it may have been deliberately introduced to produce cheaper counterfeit heparin products. "We cannot say whether it was deliberately or accidentally introduced, but we are actively working to establish this," she commented.
Woodcock also pointed out that it had not been definitely established that this contaminant had caused the increase in adverse reactions seen with heparin but said there was an intensive immunologic investigation under way to investigate whether this compound could have caused such adverse reactions when mixed with heparin.
She also noted that now that the contaminant has been identified, more rigorous tests can now be made available to detect its presence in heparin supplies.
Reviewed by Dr. Ramaz Mitaishvili and Dr.Gina Gagua
