Amylin Pharmaceuticals has won the first skirmish in its legal battle with long-time Byetta partner Eli Lilly concerning the latter's plans to promote a rival diabetes drug with Boehringer Ingelheim.

Just over a week ago, Amylin filed a lawsuit against Lilly, claiming its link-up with Boehringer is unlawful and breaches pacts covering Byetta (exenatide) and its once-weekly version Bydureon. In January, Lilly signed a wide-ranging diabetes collaboration, one of the key elements being the oral dipeptidyl peptidase-4 inhibitor Tradjenta (linagliptin). That drug was approved in the USA earlier this month.

The firm alleges that Lilly is engaging in "improper, unlawful and anticompetitive behaviour" as linagliptin will compete directly with the eventide products. Now a California court has issued a temporary restraining order (TRO) against Lilly, preventing it from proceeding with plans to use the same sales force to sell both exenatide and linagliptin.

The court has also enjoined Lilly from disclosing any confidential information about exenatide to any of its sales representatives or employees participating in the marketing, promotion or sale of the Boehringer-developed drug.

Lilly disappointed

Lilly's general counsel Robert Armitage said "we are disappointed with the court's decision", claiming that "we have complied with our contractual obligations under our agreements with Amylin in a manner fully consistent with all applicable laws". He added that the allegations "are entirely without merit and we fully expect to prevail in this litigation".

The company added that it is taking "the appropriate steps to comply with the court's order…while working to mitigate the impact of any temporary modifications to its diabetes business".