March 20 (Bloomberg) -- Baxter International Inc.'s heparin was contaminated by a cheaper ingredient in China, that country said, confirming a finding from U.S. regulators probing deaths and allergic reactions linked to the blood-thinning medicine.

Tests showed traces of a substance known as over-sulfated chondroitin sulfate, the State Food and Drug Administration in Beijing said in a statement yesterday. The contaminant, a less expensive ingredient derived from animal cartilage, isn't approved in the U.S. for medical use, said Janet Woodcock, head of the U.S. Food and Drug Administration's drug division.

The finding gives investigators a new lead in their search for the cause of the dangerous side effects that prompted Baxter to withdraw the medicine, usually made from ingredients taken from pig intestines. Baxter, based in Deerfield, Illinois, supplied half the injectable heparin used in the U.S. The FDA hasn't determined whether the compound caused the reactions.

``It does not appear to have come straight from the pig,'' Woodcock said of the contaminant during a conference call with reporters yesterday. ``It doesn't appear to be a natural contaminant that got in there. We don't know how it was introduced or why.''

Heparin is used by millions of people to prevent blood clots during dialysis, heart surgery or other circumstances.

U.S. regulators are investigating whether the ingredient was intentionally added to raw heparin from China. Adding the contaminant to raw heparin, the active component in the finished product, would have been cheaper than using the pure ingredient, according to the FDA. The agency didn't know how much money would be saved by its use, Woodcock said.

Chemically Modified

Chondroitin sulfate is taken orally as a dietary supplement to treat joint pain. The over-sulfated version found in the heparin was chemically modified to act like heparin, Woodcock said.

Over-sulfated chondroitin sulfate is generated in laboratories for experimental purposes, said Siobhan DeLancey, an FDA spokeswoman, in an interview. It is chemically altered to add additional sulfates, she said.

Two percent to 50 percent of the contaminated raw heparin samples tested by the FDA were made up of over-sulfated chondroitin sulfate, Woodcock said.

Allergic Reactions

Baxter and U.S. regulators have said allergic reactions may have been caused by raw heparin that came from China. Baxter's raw heparin was produced by Scientific Protein Laboratories, which has plants in China and Wisconsin.

The contamination was present in the powdered raw heparin purchased by Scientific Protein's plant in China, said Robert Rhoades, a pharmaceutical consultant with Becker & Associates in Washington, speaking for Scientific Protein. The company wasn't aware of the contamination at the time because it wasn't detected in the tests Scientific Protein conducted on the powder provided by suppliers, he said.

``It was undetectable by the standards that were used prior to this whole event,'' Rhoades said in an interview.

Scientific Protein purchased raw heparin from consolidators and refined it further before sending it to Baxter, which uses the ingredient to make the finished drug, Rhoades said. The consolidators obtained the ingredients from workshops in China, he said.

The contaminant ``was very likely introduced at the workshop or consolidator level,'' said Norbert Riedel, Baxter's corporate vice president and chief scientific officer, in a statement.

19 Dead

Baxter is seeking access to those suppliers to determine how the contaminant was introduced, according to the company's statement.

The FDA said in a March 5 conference call that as many as 19 people may have died after taking heparin. The FDA can't ``conclusively link'' the deaths to the contaminated heparin and the investigation is continuing, said DeLancey of the agency.

Baxter identified four cases in which patients received its drug and suffered a reaction that may have contributed to their deaths. Not enough medical data is available to reach a firm conclusion, the statement said.

Two heparin products are being pulled from the Swiss market because their active ingredients are from China, Switzerland's drugs regulator said today. There have been no reports of adverse reactions to the drugs made by G. Bichsel AG and B. Braun Medical AG, Swissmedic said in a statement.

China Investigation

China will investigate makers of chemicals that may have escaped regulation because they aren't officially classified as drug ingredients, Wu Zhen, the food and drug agency's deputy director, said March 16. The factory where the suspect raw heparin was made is classified as a chemical plant and isn't registered with China's food and drug administration, the official Xinhua News Agency reported yesterday.

Chinese regulators are trying to determine how many companies make such raw materials, and will toughen rules to make it easier to trace drug materials' origins, Wu said.

The FDA on March 14 said it hopes to place eight staff members in China to ensure food and drug safety. The FDA never inspected the heparin plant in China because of a mix-up with a supplier that has a similar name.

Pet food containing melamine, a chemical in plastic that was added to wheat gluten from China, killed and injured pets last year. Contaminants have been found in other Chinese products, including toothpaste, livestock feed and toys.

Imports of raw heparin must be tested for impurities or they will be blocked at U.S. borders, the FDA said March 14. Heparin now being used in dialysis centers has been tested and is safe, Woodcock said.

To contact the reporters on this story: Dune Lawrence in Beijing at dlawrence6@bloomberg.net; Justin Blum in Washington at jblum4@bloomberg.net

Last Updated: March 20, 2008 10:04 EDT