BEIJING - Traditional Chinese medicine experts disagree on whether natural bear bile can be replaced by artificial bile, raising questions about the need for companies that have bear farms to collect the liquid.

Guizhentang Pharmaceutical, one of China's largest bear bile medicine producers, announced plans in early February to have an initial public offering of stock in the company to raise funds that would finance an expansion of its bear farm and production.

The company opened its bear farm to reporters on Wednesday and Friday in an effort to rebut accusations that the operation was cruel to animals.

And now the focus of the discussion has expanded to the artificial substitute for natural bear bile.

"Natural bear bile cannot be replaced by artificial bile or herbs, because the natural bile of bears has a special effect that is necessary to many traditional Chinese medicines. We have no plan to halt the business of extracting bile from captive bears," the company said on its micro blog on Friday.

Zhou Chaofan, a professor of traditional Chinese medicine at China Academy of Chinese Medical Sciences, said artificial bile has only one kind of cholic acid, while natural bear bile has four other acids that improve the therapeutic effect.

"If you compare the effect of artificial bile with the natural, it's like comparing a tree to a forest," he said at a news conference on Wednesday in Hui'an, Fujian province, where Guizhentang's bear farm is located.

The company said bear bile is now used in 123 traditional Chinese medicines, and 183 pharmaceutical companies use bear bile powder in medicines.

Bear bile is used in traditional Chinese medicine because it is thought to be effective in detoxifying the body, cleaning the liver and improving vision.

But Gao Yimin, an expert on traditional Chinese medicine at the Capital Medical University, said the therapeutic importance of bear bile should not be exaggerated because it has a limited patient group. And patients with a weak spleen or stomach will vomit or their situation will become worse if they have drugs with bile.

In addition, bile from captive bears may be of lesser quality "because of the serious risk of disease of liver, gallbladder or other organs" the animals run from the extraction process, said Jiang Qi, former vice-president of Shenyang Pharmaceutical University, where a team started researching artificial bear bile in 1983.

After more than 20 years of research and hundreds of clinical trials in four famous hospitals in Shanghai and Shenyang, Liaoning province, authorities granted a patent in 2006 for the composition and method of making artificial bear bile developed at the University, saying "it is a good substitute for the natural bear bile".

But the products using it have not yet been nationally approved for mass production.

Some patients who need medicine made with bear bile expressed concern about artificial bile.

"I chose to use the medicine made of natural bile because it has been used for a long time and is effective and safe," said Xu Haohan, a patient from Shenyang, who has cholecystitis.

"I'm suspicious of this project on artificial bile. I can't verify whether it can replace natural bile, so I refuse to use it."

"But I hope there will be safe substitutes coming soon to protect bears," he said.

Hu Meidong contributed to this story.

China Daily