The US Food and Drug Administration says it will complete a review of Eli Lilly, Amylin and Alkermes' once-weekly diabetes drug candidate Bydureon within six months, making US approval a possibility in January 2012.

Bydureon was approved in the EU in June, and has already been launched in the UK. It is expected to launch in other major European countries in the near future, but has had a harder time navigating through the US regulatory process.

Last October, the FDA said it could not approve the companies' first marketing application for Bydureon, an extended-release formulation of Lilly and Amylin's Byetta (exenatide) which is given twice-daily, without more data on its how it affects the heart.

That was the second time the agency turned down Bydureon; it also declined to give a green light to the drug in March 2010 at its first bid for approval.

Last month, Lilly and its partners presented the FDA with the results of a study which showed that Bydureon did not prolong QT intervals in healthy individuals, providing reassurance of its cardiovascular safety.

"We will continue to work with the FDA through this stage of the review process," commented Christian Weyer, senior vice president for R&D at Amylin. "If approved, we believe Bydureon will be an important new option for type 2 diabetes patients, as the first once-weekly treatment available in the US."

Byetta is Amylin's biggest-selling product and was the first glucagon-like peptide-1 (GLP-1) receptor agonist to be approved for the treatment of type 2 diabetes back in 2005.

Sales have been under pressure of late, however, following approval of Novo Nordisk's rival drug Victoza (liraglutide), which requires once-daily injections, as well as new oral anti-diabetic drugs such as the DPP-IV inhibitor class, which includes Lilly and Boehringer Ingelheim's recently-approved Tradjenta (linagliptin).

Lilly and Amylin hope the new long-acting formulation will breathe new life into its GLP-1 receptor agonist franchise and help restore upwards sales growth. Byetta's worldwide sales declined 4% to $171 million in the second quarter of this year.