Employees of Boehringer Ingelheim, the German drug maker, continued to express concern over whether sales of their blood thinner, Pradaxa, could be harmed if the public learned that some patients might need regular testing for safety reasons, according to new documents unsealed by a federal judge in Illinois on Thursday.

The documents, which include a series of internal emails and memos, add to a trove of court records that were made public last week by Chief Judge David R. Herndon, of the United States District Court in East St. Louis, who is overseeing thousands of lawsuits filed by patients and their families, who say that Boehringer Ingelheim failed to properly warn them about the risks of taking Pradaxa.

Since its approval in 2010, the drug, which can cause fatal bleeding, has brought in more than $2 billion in sales in the United States, according to the research firm IMS Health. It has been prescribed to 850,000 patients, but has also been linked to more than 1,000 deaths.

Boehringer Ingelheim has stood by the drug, noting that the Food and Drug Administration has upheld its safety and that its value has been proved in clinical trials.