Investigators have found a contaminant in the blood-thinning drug heparin, the Food and Drug Administration announced today.
Those trying to determine what has caused a recent spike in allergic reactions and deaths associated with the medication now say they have found contamination only in the product whose ingredients came from China.
The FDA stopped short of saying that the problem originated in China, however, because of the complexity of the drug's supply chain.
The contaminant found in the drug acts like heparin, the FDA said, so it would not show up on traditional tests. Samples that tested positive contained 5 percent to 20 percent of the contaminant. But FDA stressed Wednesday that there is not yet a direct link between the contaminant and the adverse events.
"We do not know how it was introduced or how it got into these products," said Janet Woodcock, acting director of the FDA's Center for Drug Evaluation and Research. "We still don't know whether this inadvertently got into the supply or whether it was actually added."
The announcement today is the latest development in a heparin scare that prompted both the FDA and heparin maker Baxter Healthcare Corporation to take action.
In late February, Baxter issued a massive heparin recall and FDA regulators traveled to China to inspect its plant. Most of the raw ingredients for Baxter heparin come from Chinese suppliers, who provide the ingredients to processing plants in both China and Wisconsin before the drug arrives at its manufacturer.
The Wisconsin plant also gets raw ingredients from U.S. suppliers, but testing to date has shown no contaminants linked to the U.S. suppliers.
Baxter executives said the drug maker concluded that the problem did not occur in its New Jersey plant, which puts together the final product.
"We've excluded a number of potential causes," said Peter Arduini, president of Baxter's medication delivery business. "The active pharmaceutical ingredient is now the primary focus of our investigation."
The FDA also said that as many as 19 deaths may now be linked to tainted heparin, up from their projection of four last week. Baxter contended that the number remained lower when the cases are considered according to more stringent scenarios.
"It's too early to conclude that the deaths were caused by the allergic reaction," Arduini said. "Just because there's a report that a patient took heparin doesn't mean that the heparin caused the event."
Arduini added that investigators are also not certain whether all of those deaths are associated with Baxter's heparin.
With more and more drug ingredients coming from overseas, the FDA is facing scrutiny about how often foreign plants are inspected and how to best guarantee the safety of the food and drug supply.
The FDA said that in fiscal 2007 it conducted more than 1,000 inspections, a record for the agency.
"I'm not by any stretch of the imagination indicating that we do not have to do more," FDA commissioner Andrew von Eschenbach said today. "At the same time, it's a matter of doing the right thing in the right way."