Eli Lilly and Amylin Pharmaceuticals have presented promising data from a late-stage trial of a slow-release version of their type 2 diabetes treatment Byetta.

A head-to-head study of the firm’s Byetta (exenatide), the approved twice-daily version, and the new once-weekly formulation Byetta LAR demonstrated that the latter showed statistical superiority in terms of controlling blood glucose levels. The randomised, non-inferiority Phase III study involved 295 patients with type 2 diabetes who had failed to achieve acceptable blood glucose control with diet and exercise, with or without one or more oral antidiabetic therapies.

After 30 weeks, patients who received Byetta LAR, which uses a proprietary technology for long-acting medications developed by Alkermes, achieved a 1.9% improvement in A1C levels from baseline, compared to a 1.5% for those on Byetta. Both groups experienced significant weight loss and once-weekly exenatide was associated with approximately 30% less nausea than the original drug.

Orville Kolterman, senior vice president of clinical and regulatory affairs at Amylin, said that “with these safety and efficacy data in hand, we are working diligently to complete the remaining steps required for our once-weekly exenatide regulatory submission by the end of the first half of 2009".

Some analysts have suggested that the new formulation could have peak sales of $3 billion but Philip Nadeau of Cowen & Co said in a research note that "while the trial was positive, we believe that the difference between Byetta LAR and Byetta was somewhat below expectations." Also a 2009 filing seems to be a bit on the conservative side for many analysts.

Another possible fly in the ointment could be concerns that have risen about the safety of Byetta, which contributed $164.8 million to Lilly’s coffers in the third quarter. Just a fortnight ago, the drug was the subject of a safety elert issued by the US Food and Drug Administration concerning the possible risk of pancreatitis associated with taking the treatment.