Regulators in the U.S. are warning drugmakers, suppliers and health professionals to be on the alert for counterfeit medicine additives that substitute a poison used in antifreeze for a common sweetener.

The Food and Drug Administration knows of no contamination cases in the U.S. like those that caused deaths in Panama, Haiti and elsewhere in recent years, the agency said in a statement posted on its Web site.

Some Chinese suppliers have used poisonous diethyline glycol, or DEG, as a substitute for glycerin, a more expensive sweet syrup, in cough medicine, fever medication and injectable drugs, the New York Times reported today. Researchers estimate that thousands of deaths worldwide have been caused by drugs contaminated by DEG, an industrial solvent and an ingredient in some antifreeze, the newspaper said.

The FDA ''is emphasizing the importance of testing glycerin for DEG due to the serious nature of this potentially fatal problem in combination with the global nature of the pharmaceutical supply chain and problems that continue to occur,'' the agency said in the statement released May 4.

Tainted cough syrup caused more than 40 deaths in Panama in 2006, and at least 80 children in Haiti died of tainted acetaminophen syrup in late 1995 and early 1996, the FDA said. Similar poisonings were reported in the 1990s in Argentina, Bangladesh, India and Nigeria.

Manufacturing and pharmacist organizations are working with the FDA to ''put into place controls to ensure that this problem does not happen in the U.S. or elsewhere,'' the agency said.

The Federal Food, Drug and Cosmetics Act, giving the FDA much of its authority to regulate drug safety, was enacted after more than 100 people in the U.S. died in 1937 from DEG contamination of a drug used to treat infections.

U.S. agencies also are investigating adulteration of food additives from China in the deaths of cats and dogs that ate pet food containing melamine, used to make plastic kitchen utensils and fertilizers.

To contact the reporter on this story: Larry Liebert in Washington at