The U.S. Food and Drug Administration (FDA) said it believes the blood thinning drug heparin, which may have caused more than 80 deaths, was deliberately contaminated. The drug's manufacturer, Baxter International, had previously made the same claim.

Baxter issued a recall for heparin earlier this year after reports of harmful side effects began to appear. Tainted heparin, produced by other manufacturers, has also turned up in other countries, according to regulators.

Executives at Baxter and at Scientific Protein Laboratories, a Baxter supplier, testified before a Congressional committee, maintaining the main ingredient in the drug was already contaminated before it reached the factory in China where the drug was produced.

Baxter CEO Robert Parkinson told lawmakers that the companies now believe that there was a deliberate scheme to alter the ingredients of the drug. The FDA said it concurs, although the agency admits it has no proof.

Some samples of heparin submitted to lab analysis were found to contain a cheaper substance known as over-sulfated chondroitin sulfate. Both the company and the FDA said over-sulfated chondroitin sulfate is not an approved ingredient in the drug, designed to reduce blood clotting.

The FDA came in for more criticism in the wake of the heparin contamination.

A Congressional investigator told Congress that the FDA bungled a scheduled inspection of the Scientific Protein plant in China because regulators went to the wrong plant. Had they gone to the correct plant, said David Nelson, they might have been able to head off the contaminated drug from reaching the U.S. market.

Nelson also told lawmakers that he questioned whether inspections of the plant, conducted by Baxter International, were adequate. Rep. John Dingell (D-MI) chalked it up to another example of an FDA "woefully lacking" in personnel, policy and will to do its job.


Scientists at MIT earlier said heir tests have identified the contaminate in the blood thinning drug heparin, which has caused a fatal allergic reaction in some people who took it. They identify the chemical as oversulfated chondroitin.

The U.S. Food and Drug Administration came to the same conclusion, but their finding was disputed by China, which produces the drug.

Writing in the New England Journal of Medicine, Ram Sasisekharan and his colleagues at MIT said the chemical in heparin appears to cause severe allergic reactions and abnormally low blood pressure.

"These results provide a potential link between the presence of chemical contaminant in heparin and the clinical symptoms observed in affected patients," Sasisekharan said.

U.S. health officials says as many as 81 patients in the U.S. died soon after taking the tainted heparin. Their symptoms included swelling of the larynx and low blood pressure.

Last week an official of the Chinese National Institute for the Control of Pharmaceutical and Biological Products said the substance identified as a contaminate could not be the cause of the adverse reactions reported among heparin users. The official said the same batch of the drug had been distributed in ten other countries, but there had been no reports of similar allergic reactions.

But the company making the drug appears to believe otherwise. In February, Baxter International stopped manufacturing multiple-dose vials of heparin.

Heparin is derived from pig intestines and other animal tissues, much of it produced in small Chinese workshops. Serious reactions to the drug have included difficulty breathing, nausea, vomiting, excessive sweating, and rapidly falling blood pressure that can lead to life-threatening shock.