Infographics on Anticoagulants
"We're alarmed that one of our products was used in what appears to have been a deliberate scheme to adulterate a life-saving medication, and that people have suffered as a result," Baxter chief executive Robert Parkinson told a US Congress panel.
"We deeply regret that this has happened, and I feel a strong sense of personal responsibility for these circumstances," he told a subpanel of the House of Representatives' Energy and Commerce Committee.
"Patient safety is our number one priority, and we deeply regret the impact this contamination in Baxter's heparin has had on patients," Parkinson told the subcommittee on oversight and investigations.
The US Food and Drug Administration (FDA) first received reports of allergic reactions to heparin in November 2007.
At least 81 deaths have been linked to the drug, while 785 severe allergic reactions have been reported.
The FDA has identified the toxic substance in heparin as a synthetic compound called oversulfated chondroitin sulfate (OSCS).
Heparin, a blood thinner used by millions of patients during kidney dialysis and heart surgery to prevent blood clots, is normally produced from pig intestines. Using OSCS as an alternative is cheaper.
Chinese officials rejected the FDA's conclusions, saying the chemical had nothing to do with the allergies and deaths.
The United States now tests heparin imports for OSCS and the stocks of the drug do not present any risks, the FDA says.
FDA officials have said the contaminated batches came from factories in China that make the drug for Baxter International, which recalled its heparin in February after dozens of deaths in the United States were reported.
US health authorities said Chinese companies have also supplied contaminated heparin to Australia, Canada, China, Denmark, France, Germany, Italy, Japan, the Netherlands and New Zealand.
"We have been able to trace the contaminant to 12 different Chinese companies," Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research, told the House panel.
The active ingredients of Baxter's heparin were produced by one of its American suppliers, Scientific Protein Laboratories (SPL), at a plant in Changzhou, China.
Democratic Representative Bart Stupak, the chairman of the oversight and investigations subcommittee, said he remained unsure that heparin was deliberately tainted.
"Today, it's not known whether this contaminant entered the supply chain accidentally or was introduced intentionally," Stupak said.
The lawmaker, whose panel also heard testimony from the families of victims of tainted heparin, wagged his finger at the FDA and the pharmaceutical firms.
"While much of this subcommittee's ire regarding the safety of drugs in this country has been directed towards FDA, perhaps a greater responsibility to ensure the safety of drugs in this country lies with drug companies themselves," he said.
"Make no mistake about it; both Baxter and SPL have failed the American public," Stupak said.