Long-acting diabetes med Bydureon passed a crucial test of its effects on heart rhythms, said the drug’s developers Amylin, Eli Lilly and Alkermes. One analyst said the results may help the drug right itself after a spate of regulatory delays.

The clinical trial showed Bydureon, even at high concentrations, does not prolong the QT interval, the amount of time the heart’s electrical system takes to recharge after each beat. The companies said they plan to submit the results to the FDA in the third quarter as part of their reply to a complete response letter the agency had sent the companies in October.

A once-a-week injectable form of exenatide, the active ingredient in Byetta, Bydureon was meant to go up against Victoza from Novo Nordisk. Victoza, which is injected once a day, had sales of $433 million in 2010, its first year on the market.

Bydureon’s October CRL followed one issued in April 2010, and the delays pushed approval out to at least 2012. Then, this year the drug’s developers dropped another bombshell, saying the findings of the DURATION-6 study showed that Bydureon failed to manage blood glucose levels as well as Victoza.

The view at that time was that the results, coupled with the delay, would make it harder for Bydureon to penetrate the GLP-1 market. Could the results from the heart study, known as a tQT study, revive Bydureon?

“After a string of regulatory delays, Bydureon’s clean bill of health from its tQT study lays out a clear path to approval,” wrote Credit Suisse analyst Catherine Arnold today in a note to investors called “Bydureon Back on Track!”, adding that an OK from regulators is “likely” by early 2012. Bydureon was approved in the EU earlier this year.

The analyst also downplayed the DURATION-6 results, predicting that they won’t provide much of an impediment to sales given the drug’s once-weekly dosing, and calling Bydureon the “most compelling proposition” in its class.

“Most physicians we spoke to at the recent meeting of the American Diabetes Association said they would show strong preference for Bydureon,” she wrote. “They did not believe that Bydureon failing the non-inferiority test vs. Victoza in the DURATION 6 study was clinically meaningful, especially given the efficacy seen in the multitude of other trials.”