Though 10 of the 61 patients who suffered adverse reactions from receiving Avastin injections have recovered, the source and use of the controversial drug is still unknown.

Last week, 116 patients received Avastin injections to treat macular degeneration at the Shanghai No 1 People's Hospital. Sixty-one of the patients experienced negative symptoms like pain, red eyes and unclear vision, and returned to hospital for further treatment.

The hospital said on Monday that most of the patients who suffered adverse reactions had improved, and 10 had recovered and been released from hospital. But it would not give more information.

Avastin, the trade name of bevacizumab, is marketed by Swiss pharmaceutical giant Roche. It first received approval from the US Food and Drug Administration in 2004 to treat metastatic colorectal cancer.

This February, Avastin received approval from China's State Food and Drug Administration to enter the Chinese mainland for the treatment of colorectal cancer, but it has not yet been sold in the market.

"So far, the drug cannot be obtained though formal channels on the Chinese mainland," Cao Yong, a spokesman of Shanghai Roche Pharmaceutical Company, was quoted by the National Business Daily as saying.

"And Avastin is only approved for use for the treatment of metastatic colorectal cancer," he said.

According to a regulation on imported drugs released by the State Food and Drug Administration, all imported drugs should have an imported drug certificate issued by the Ministry of Health. This certificate states the drug's name, producing country and manufacturer.

"The use of imported drugs must comply with the requirements of health authorities," said Tang Jianli, a lawyer from Shanghai Haida Law Office, who is experienced in medical disputes.

"It's illegal for hospitals to use drugs without complying with regulations from the State Food and Drug Administration," Tang said.

An insider in Beijing said it is very common for hospitals to use Avastin to treat macular degeneration, though it is not officially approved.

"Many doctors recommend this drug as effective treatment, and it is cheaper than other officially-approved drugs," the insider said.

A woman from Beijing who declined to be named told China Daily that her mother has received this kind of treatment on her eyes for a few months.

"In March this year, I took my 84-year-old mother to the Beijing People's Hospital for macular degeneration. The doctor recommended Avastin to treat my mother's eyes," she said on Tuesday.

"When I went to pay for the medical expenses, medical staff asked me to pay the fees separately. So I paid the operation fee normally and paid the drug fee to another man," she said. "But the man didn't wear a white coat like doctors usually wear. I think he might not be a doctor."

"What's more, he refused to give me any receipt after I paid the fees. I expressed my doubt and confusion, but the man just said 'you can choose not to use this drug'," she said. "To cure my mother's eyes. I had to accept it."

The woman said she paid about 1,000 yuan (US$148) for operation fees, and 450 yuan for each shot of the drug.

"So far, my mother has been injected three times with such drugs. But some patients I met in the hospital have been treated with this drug since 2007. It's hard to believe and understand what is going on," the woman said.

The Ministry of Health is investigating the incident with the State Food and Drug Administration.