SFDA’s website published a statement on May 6 that quoted Chinese experts claiming inconclusive evidence supporting a direct link between the heparin substitute (hypersulphated chondroitin sulphate) and US deaths related to heparin.

In the statement distributed by the SFDA, China reiterated its earlier assessment that the cause of the U.S. deaths can't be proven to be over-sulfated chondroitin sulfate, and said it needs more information from Baxter to identify the cause of the problems.

"It is essential to conduct a thorough analysis on raw materials, excipients, manufacturing process, clinical use and patient status to further identify the reasons," the statement said.

Jin Shaohong, deputy director of China's National Institute for the Control of Pharmaceutical and Biological Products who headed the Chinese probe into the US heparin deaths, told a press conference earlier that according to a current heparin-related adverse event study, "the direct causal relationship between the “heparin-like substance” (hypersulphated chondroitin sulphate) and the clinical cases of deaths cannot yet be confirmed."

Jin said at present, apart from the U.S. and Germany, more than 10 countries using heparin products containing "heparin-like substance" had not reported any cases of adverse reactions. "U.S. experts also analyzed that the concentrated heparin adverse events which occurred in the U.S. had a certain relationship with the large dose of clinical use and quick injecting speed," he said.

The US-based Covidien Pharmaceutical Co. and B. Braun Pharmaceutical Co. also bought the raw heparin containing the substance from the US-based Scientific Protein Laboratories (SPL) for injection production, but no serious adverse reactions occurred, Jin said. The SPL owns the majority stake of a Chinese factory in Changzhou that supplies ingredients for heparin.

Deerfield-based Baxter and SPL said April 29 that the problem stems from Scientific Protein's suppliers. The contamination occurred before reaching Scientific Protein's laboratory in China and was “deliberate and widespread,” according to SPL.

China's government is still investigating how over-sulfated chondroitin sulfate was added to the heparin, Yan Jiangying, spokeswoman for the State Food and Drug Administration, said at the latest briefing in Beijing. Once the cause of the contamination is identified, China “will handle the issue in accordance with laws” if domestic companies caused the problems, the statement said.

Jin said that serious adverse reactions also occurred in some batches of heparin injection products with raw materials containing no heparin-like substance. He said adverse reaction cases in the U.S. were all reported by patients themselves via a spontaneous reporting system, lacking doctors' confirmation.

Jin also said that Baxter International Inc, the U.S. drugmaker that recalled batches of the drug heparin, failed to carry out “necessary” cooperation with the Chinese experts, who were sent to the U.S. to investigate the cause of the contamination. “The Chinese experts has asked for the production records, samples and recalled heparins, and Baxter did not provide necessary cooperation”, said Jin. He also said Baxter's move was not conducive to the investigation and the Chinese experts felt “deeply regretful”. He said further analysis was needed to decide the relationship between heparin-like substance and the deaths.

However, in an e-mailed response to the Chinese drug regulator's comments, Seok Lin Hong, Baxter's Singapore-based communications director for Asia Pacific, said the company had cooperated with the administration. “Baxter agreed to provide samples to the SFDA in response to their request,” the statement said. “We have been cooperating with all parties involved in the heparin situation and we will seek to understand any concerns to the contrary.”

Allergic reactions to Baxter's heparin led to a U.S. recall in January and February and an investigation by regulators in both the U.S. and China, where the drug's main ingredient was made. Officials of the two nations clashed over the cause of the reactions, with the U.S. blaming a substance known as over- sulfated chondroitin sulfate in samples of the drug made in China.

Since January 2007, 81 people have died after allergic reactions, the U.S. Food and Drug Administration said on April 21. Tainted heparin made by other drugmakers has been found in more than a dozen countries since Baxter's recall, and regulators have said they don't know how it was introduced.