While China’s top drug safety agency, the State Food and Drug Administration, has ordered a general step-up of oversight covering heparin production, a second US company has recalled the blood thinner.

The Chinese regulator ordered that producers of the active ingredient in heparin can only get the substance from registered, approved producers. Also, authorities have imposed additional checks on the quality and safety of the drug's raw ingredients.

Meanwhile, B. Braun Medical Inc. recalled its heparin products in the U.S. and Canada, the company announced yesterday. Apparently the same contaminant that was earlier detected in Baxter's product was also found in B. Braun's heparin. The substance was provided by Scientific Protein Laboratories, the same supplier that Baxter had.

The US Food and Drug Administration has announced that it has identified the mysterious substance which contaminated some lots of the recalled blood-thinner heparin sold by Baxter International Inc. It is a man-made chemical compound known as over-sulfated chondroitin sulfate which is much cheaper than heparin.

It appears that heparin was cut with the similar substance to reduce costs. This is further reinforced by the fact that the chondroitin sulfate was modified to mimic heparin. Normal chondroitin sulfate is used as a supplement by people suffering from joint problems.

Heparin, made from ingredients extracted from pig intestines, is used to prevent blood clots in millions of people with heart conditions, kidney disease and in surgery. The contaminant made up between 2 and 50 percent of the heparin samples tested by the FDA, which did not assert directly that the heparin was counterfeited on purpose.

Last month, Baxter first recalled nine lots of the heparin after receiving hundreds of reports of allergic reactions possibly linked to heparin, as well as reports of four deaths. Shortly after, the company recalled all remaining heparin products. The other major U.S. heparin supplier, APP Pharmaceuticals Inc, ramped up production to avoid a drug shortage after the Baxter recall. Tests on APP's heparin have not turned up any contamination.