Amylin Pharmaceuticals Inc. said Thursday that a federal court has issued an injunction preventing drug development partner Eli Lilly and Co. from using the same sales force to sell an Amylin-developed diabetes treatment and a competitor's.

Amylin says the temporary restraining order prevents Lilly from continuing with a plan to sell both Byetta and Boehringer Ingelheim's linagliptin. Amylin and Indianapolis-based Lilly entered an agreement in 2002 to develop and sell Byetta, a type 2 diabetes treatment.

San Diego-based Amylin filed a lawsuit against Lilly earlier this month, accusing the drugmaker of breaking their commercialization deal for diabetes drugs by teaming with Boehringer Ingelheim to develop and sell a competing product.

Lilly entered a development agreement with Germany's Boehringer Ingelheim in January. Earlier this month, regulators approved linagliptin, which also treats type 2 diabetes. Amylin then filed the lawsuit against Lilly over that arrangement.

Lilly says it is disappointed in the court's decision but will take the necessary steps to comply with the order.

"We believe that Amylin's allegations against Lilly are entirely without merit and we fully expect to prevail in this litigation," Lilly senior vice president and general counsel Robert A. Armitage said in a statement.

Company spokesman Mark Taylor declined to comment beyond the statement, which was issued late Wednesday night.

The injunction also prevents Lilly from disclosing any confidential information about Byetta, known generically as exenatide, to sales representatives selling linagliptin, which goes by the brand name Tradjenta.

Type 2 is the most common form of diabetes. People with the disease have trouble breaking down carbohydrates because their bodies have become resistant to the protein insulin. They are at higher risk for heart attacks, kidney problems, blindness and other serious complications.

Lilly said in January it would pay Boehringer about $387 million as part of a joint bid to develop and sell up to five drugs. The companies will split revenue from any approved drugs, not counting costs for making and selling the product. Each drugmaker also will receive payments based on whether their products reach certain milestones, like submissions for approval.

Amylin and Lilly also are seeking regulatory approval for a longer-lasting version of Byetta called Bydureon. Amylin has said it plans to continue working with Lilly, but that company's deal with Boehringer amounts to anticompetitive behavior.

Lilly has said patients and doctors need choices to fight diabetes, and its strategy for the chronic disease involves offering a broad range of options. It also said injectables like Byetta generally compete with other injectables, not tablets like Tradjenta.