The number of suspicious deaths in the United States linked to the blood thinner heparin has risen to 62 from 19, with most of them reported this past December, January and February, according to the first detailed analyses of heparin fatalities by the Food and Drug Administration.
The F.D.A. is still investigating whether those deaths and hundreds of allergic reactions were caused by a heparinlike contaminant made in China that was added to the drug somewhere during the manufacturing process.
The drug agency defined suspicious deaths as those involving one or more allergic reactions or a drop in blood pressure. There have been no reports of deaths since the end of February, after Baxter International recalled heparin made with ingredients from a Chinese supplier.
The agency’s Web site reported Tuesday that the 62 deaths covered a 14-month period that began in January 2007. In comparison, the agency said, there were three suspicious deaths involving heparin in all of 2006.
The F.D.A. had earlier identified the contaminant as a chemically altered substance that slipped through standard testing screens because it mimicked heparin. The agency was able to spot the additive only by using a more sophisticated test.
Investigators have not yet established how or why the additive, called oversulfated chondroitin sulfate, ended up in heparin, though the fact that it is cheaper to make than the actual drug points to the possible involvement of counterfeiters.
In addition to Baxter, companies that have recalled heparin products made with Chinese ingredients include Covidien, formerly Tyco Healthcare, and B. Braun. Both Covidien and Braun said that they had received no reports of adverse reactions from the heparin and that the recalls had been undertaken merely as a precaution.
Similar recalls of the drug have occurred in Germany, Denmark, France, Italy and Japan.
Heparin is made from the mucous membranes in pig intestines. It is commonly used in dialysis and in many types of surgery.
Drug regulators in China, the world’s biggest supplier of heparin ingredients, have said they are tightening supervision over production of the drug, which involves thousands of small family workshops that gather and treat the raw material from pig intestines.