Tainted heparin manufactured by Baxter International has been directly linked to the deaths of three people, according to the Food & Drug Administration (FDA). Earlier this year, the FDA had received more than 90 reports of deaths and more than 1,000 adverse events associated with patients in the U.S. who had one or more allergic reactions to heparin products, including those sold by Baxter since Jan. 1, 2007.
In January, Baxter International recalled nearly all its heparin injections in the US after some patients experienced extreme – and in some cases fatal – allergic reactions, including difficulty breathing, nausea, vomiting, excessive sweating, and rapidly falling blood pressure that was life threatening after being administered the products. There have been similar recalls by other manufacturers of Chinese-sourced heparin in Denmark, Italy, France Germany and Japan. In total, the FDA said tainted heparin has been identified in 12 countries. In the US, other heparin suppliers have issued precautionary recalls, and some medical devices makers have also recalled heparin-coated products.
In March, the FDA confirmed that it had found oversulfated chondroitin sulfate in samples of the active ingredient used in Baxter heparin. The FDA said the chondroitin sulfate was molecularly changed to mimic heparin’s blood-clotting properties. That ingredient was supplied to Baxter by Changzhou SPL, a Chinese plant partially owned by Wisconsin-based Scientific Protein Laboratories. It costs a fraction of the ingredient usually used in heparin, and producers may have used it in an attempt to cut costs.
In April, a research team, led by scientists at MIT, found that the chondroitin sulfate activates two inflammatory pathways: one that initiates blood clotting and dilation of the blood vessels, and one that produces anaphylactic toxins. The first leads to a dangerous decrease in blood pressure, the second a serious allergic reaction. In blinded laboratory tests, the contaminated heparin activated the biological pathways, while normal heparin did not. In the study, pigs treated with tainted heparin exhibited side effects similar to those seen in humans.
According to an article in The Chicago Tribune, the FDA said it completed its review of 93 death reports related to heparin that the agency received from Jan. 1 to March 31, when reports of heparin adverse reactions peaked. Of 10 reports of death from severe anaphylaxis or hypotension, three of those could be traced to lot numbers of Baxter products that tested positive for chondroitin sulfate. Heparin lot numbers were not known for the other seven deaths, so the FDA could not determine if those patients received tainted heparin.
Of the remaining 83 reports, the FDA described 13 as “potential complications of heparin use” such as bleeding; 25 cases were due to causes unrelated to heparin use such as pneumonia, sepsis and kidney failure. The FDA said that there was insufficient information available about the remaining 45 fatalities to conclusively cite a cause of death.