Contaminated blood thinner heparin now called a worldwide problem
Federal regulators bar a Chinese-made version of the drug, blamed for as many as 81 deaths. They announce a breakthrough in understanding how it sickened patients.
WASHINGTON — A contaminated blood thinner from China suspected in dozens of U.S. deaths has become a worldwide public health problem, with 10 other countries detecting the often-toxic ingredient, federal investigators said Monday.
The compound, which in tests mimics the real blood thinner heparin but costs less to make, may have been added deliberately somewhere along a production chain that began on farms in China, beyond the reach of U.S. regulators.
Food and Drug Administration officials issued a warning letter Monday that banned future U.S. shipments from the plant in China that supplied the widely used blood thinner until the safety issues are resolved. And officials raised the possible death toll from 62 to 81.
At the same time, the FDA announced a major scientific breakthrough in its attempt to understand how patients got sick from the contaminated heparin.
The developments came on the eve of a congressional hearing expected to show that the FDA lacks the resources to carry out adequate inspection of thousands of foreign facilities now producing a significant share of the medications consumed here.
"Contamination of the heparin supply is a worldwide problem," said Dr. Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research. Thus far in the investigation, about a dozen Chinese facilities of varying sizes have been identified as being part of the supply chain that handled contaminated heparin.
The widely used blood thinner is given to patients to prevent dangerous clots when they undergo kidney dialysis or heart surgery. The ingredient that contaminated the drug, a chemically modified form of a common nutritional supplement, has been shown in laboratory and animal tests to cause the dangerous reactions that some patients experienced, Woodcock said. These included a sudden drop in blood pressure, leading to shock.
Woodcock explained that the contaminant -- a compound called an over-sulfated chondroitin sulfate -- can trigger chemicals in blood cells that produce serious allergic-type reactions.
These chemicals, called blood mediators, are often spurred into action when a wound is opened, helping to generate new blood vessels around the wound and drawing in antibodies to clean up damaged areas, said Marilyn Halonen, a pharmacology professor at the University of Arizona.
But blood mediators also can cause a drop in blood pressure and other reactions in patients who receive large doses of contaminated heparin.
