The second round in a legal battle with long-time Byetta partner Amylin has gone to Eli Lilly, which is also promoting a rival diabetes drug with Boehringer Ingelheim.

Last month a court in California has issued a temporary restraining order (TRO) against Lilly, preventing it from proceeding with plans to use the same sales force to sell both Byetta (exenatide) and Boehringer's recently-approved oral dipeptidyl peptidase-4 inhibitor Tradjenta (linagliptin). Amylin claims that the link-up with German firm is unlawful and breaches pacts covering Byetta and its once-weekly version Bydureon.

The TRO also stopped Lilly from disclosing any confidential information about exenatide to any of its employees participating in the marketing, promotion or sale of the Boehringer-developed drug. However, the Caifornian court has now ruled in Lilly's favour and lifted the TRO and denied Amylin's request for a preliminary injunction that sought to impose restrictions on the Lilly diabetes sales force "and other relief".

The US major's general counsel, Robert Armitage, said the firm was pleased with the court's decision, saying "we have complied with our contractual obligations under our agreements with Amylin, and done so in a manner fully consistent with all applicable laws". He claimed that the allegations "are entirely without merit and we fully expect to prevail in this litigation."

Amylin was clearly less pleased, saying it "continues to believe that Lilly's conduct violates our diabetes collaboration agreements, is anti-competitive and limits patients' treatment options". The San Diego-based firm added that "it is important to note that the court's decision did not make any findings on the merits of our claims, but merely declines to award injunctive relief, based on the conclusion that monetary damages would be sufficient".

Amylin concluded by saying that "we intend to vigorously pursue the litigation to enforce our legal and contractual rights".