Drug News
Contaminant in heparin identified scientifically
By Sue Mueller
Apr 24, 2008 - 4:49:28 PM

THURSDAY April 24, 2008 (foodconsumer.org) -- Now there is some scientific evidence to prove that the contaminant found in heparin associated with hundreds of allergic reasons and up to 81 deaths is a man-made chemical known as oversulfated chondroitin sulfate, according to a new study.

Chondroitin sulfate naturally occurs in animal cartilage and is often used as supplements to relieve symptoms of arthritis.  But oversulfated chondroitin sulfate (OSCS) does not exist naturally.

For the study published on Wednesday in Nature Biotechnology, researchers at Massachusetts Institute of Technology, the FDA and other organizations used sophisticated analytical techniques to completely characterize the contaminant present in tainted heparin.

The researchers analyzed six heparin preparations linked with adverse reactions in patients and four preparations that had not been associated with adverse events.

They found all the heparin preparations linked with allergic reactions contained a contaminant similar chemically to synthesized OSCS.

"This study also provides the scientific groundwork for critical improvements in screening practices that can now be applied to monitor heparin, thus ensuring patient safety," Ram Sasisekharan, senior author of the study said in a statement.

In another paper simultaneously published in the New England Journal of Medicine, the researchers states in their report that the regulators now have a validated procedure to detect contaminated heparin.

The procedure was detailed in the NEJM and is ready to be used to detect oversulfated chondroitin sulfate.  In the study, heparin contaminated with OSCS and synthesized OSCS were tested and found they caused allergic reactions in pigs similar to those observed in patients.

Chinese officials early on Monday disputed the FDA speculation and claimed that the oversulfated chondroitin sulfate is not the root cause for the allergic reactions patients who used heparin experienced because the same adverse effects were also observed in patients who used heparin without the contaminant.

Heparin associated with allergic reactions and deaths was made of a key ingredient prepared by a Chinese company that is solely controlled by a Wisconsin company.

Jin Shaohong, a top official with the Chinese National institute for the Control of Pharmaceutical and Biological Products, also claimed that a key ingredient with the contaminant was also used by other countries to make other brands of heparin, but no adverse effects were reported.

But Baxter International, the maker of troubled heparin, disputed the Chinese officials’ statement and claimed that evidence is strong that the contaminant is the cause.  The company recognized though that only four deaths were associated with its heparin and is now considering discontinuation of its heparin business.

Although the current studies suggested a possibility, direct evidence is lacking to say oversulfated chondroitin sulfate is the cause for human allergic reactions because the contaminant could not be tested for its safety in humans.

But at least, the U.S. regulators and others now may a tool in hands to distinguish the contaminated heparin from the uncontaminated.