TUBE TESTING: A laboratorian works at a pharmaceutical company in Shanxi Province. There are on average more than 300 new drugs invented each day by Chinese pharmaceutical companies (FAN MINDA)

Eighty-four-year-old Zhang Zuning has been in a seesaw battle with the well-known German pharmaceutical manufacturer Bayer Group for more than six years.

In October 2006, Zhang, a retired employee of Beijing-based Zizhu Pharmaceutical, agreed to participate in a clinical trial of rivaroxaban, an anti-blood-clotting medicine manufactured by Bayer, when she was about to undergo artificial joint replacement surgery on her left knee in the Peking University People's Hospital in Beijing. Zhang took the experimental anticoagulant, designated BAY59-7939, from October 23 to November 6.

On November 7, Zhang showed symptoms of acute shock during a routine pre-operative x-ray of her veins. Deterioration of her condition forced her to return to the hospital the next day. According to the hospital, her complications may have been caused by the anticoagulant.

Bayer paid her less than 3,300 yuan ($531) but denied her any further compensation, claiming the venogram caused the symptoms.

Canadian and EU authorities approved rivaroxaban in 2008 and the U.S. Food and Drug Administration approved it in 2011. It is marketed in some countries under the brand name Xarelto.

Zhang and her son, Liao Zhijie, sued Bayer and Peking University People's Hospital and asked for 150,000 euros ($192,300) in compensation. In February 2013, the Chaoyang District Court in Beijing ordered Bayer to pay 50,000 euros ($64,100) to Zhang, who was not satisfied and decided to lodge an appeal.

"The compensation is quite low and Bayer refused to reveal the insurance items they signed with the insurance company," Liao said. "What we know is that the highest compensation would be half a million euros if the subject has an accident."

Helpless subjects

It is not the first time for pharmaceutical test subjects in China to be in the public eye. Medicine produced by American pharmaceutical company Pfizer was implicated in the death of Beijing resident Wang Liying in 2007.

Wang was diagnosed with terminal gastric cancer in Beijing's Ditan Hospital in 2006 at the age of 54.

She was running out of options. In March 2007, the hospital suggested she take part in a clinical trial of a new medicine from Pfizer called SU011248.

Pfizer told Wang that the drug needed to be tested on gastric cancer patients and had already proven effective on other cancers.

Before signing a 41-page agreement, Wang and her husband Shi Deyong researched the potential side effects of the drug. "We received documents saying there are very rare possibilities for patients to have a sharp decrease in blood platelets, which might cause death," Shi said. "The agreement said they would provide compensation for the negative effects of the medicine but didn't provide details of how much."

This rare possibility happened to fall on Wang, who died one month later of a cerebral hemorrhage. Shi then sued Pfizer and the Ditan Hospital for the accident and a court ruled in 2011 that Pfizer should pay Wang's family 300,000 yuan ($48,270) in compensation.

Wang Yue, a health law professor at Peking University, revealed that there are about half a million Chinese test subjects participating in clinical trials for more than 800 new drugs every year. Western pharmaceutical companies are a major source of demand for the trials.