A company spokesman told Reuters about 4,000 Lilly employees will be eligible for the program.
"We're trying to lower our headcount ahead of the restructuring and get us closer to the desired number," Lilly spokesman Ed Sagebiel told Reuters.
He said the offers have been extended to representatives in the company's U.S. diabetes, neuroscience and osteoporosis sales force.
The restructuring, to be announced in November and begin in January, will reduce the size of Lilly's sales territories. Smaller territories, each with one sales representative, would allow a better focus on the fewer doctors within each of the tapered regions, Sagebiel told Reuters.
The reductions also are a response to the scheduled 2011 U.S. patent expiration on Lilly's best-selling Zyprexa schizophrenia drug, Sagebiel confirmed.
The company needs to replace nearly 60 percent of the revenue it will lose between 2011 and 2014 when patents on Zyprexa and other top drugs become available to cheaper generic competitors.