The five defendents, from a pharmaceutical company in northwestern China, were blamed for allowing a fake chemical to be used in the production of a drug for treating liver and gallbladder diseases, Xinhua news agency reported.
A court in southern China's Guangzhou city on Wednesday heard that Niu Zhongren, the company's medicine buyer, bought the fake chemical, diglycol, in September 2005 to be used in the medicine.
In April 2006, the drops were administered to 15 patients in a hospital in Guangzhou and 13 subsequently died after suffering kidney failure, the court heard, according to Xinhua.
Niu failed to check the qualifications of the medicine dealer from whom he bought the killer drug.
The company was informed before the deaths that the suspicious chemical was fake, but managers turned a blind eye, the court heard.
Prosecutors said the company, which has since been shut down, also forged documents.
China has been struggling to restore confidence in its corruption-wracked food and drug industries after a series of high-profile scandals.
The former head of the State Food and Drug Administration, Zheng Xiaoyu, was executed last month after his conviction for taking bribes to approve hundreds of medicines, some of which proved dangerous.