US drug regulators have awarded fast-track status to Sanofi-Aventis’ heart drug Multaq (dronedarone), two years after first issuing it a non-approvable letter.

Multaq, a multi-channel blocker that affects calcium, potassium and sodium blockers and has anti-adrenergic properties, is being developed to treat atrial fibrillation – an irregular beating of the heart thought to affect some 2.5 million people in the USA alone and an additional 4.5 million in Europe, where the drug is also filed for approval.

The news of the Food and Drug Administration’s turnaround follows results from a landmark study earlier this year showing Multaq cut the risk of cardiovascular death 30% and the risk of first hospitalisation for cardiovascular complications by 25% in AF patients. Dronedarone, says Sanofi-Aventis, is the first safe treatment for atrial fibrillation that has been demonstrated to reduce cardiovascular hospitalisation or mortality in patients with AF; patients suffering from atrial fibrillation have twice the risk of death, as well as an increased risk of stroke and cardiovascular complications.

In 2006, the agency sent Sanofi-Aventis a ‘not-approvable’ letter for Multaq, because the agency felt that more clinical evidence of the drug’s efficacy and safety was required. Just one week later, the Franco-German firm decided to withdraw its submission in Europe after the region’s scientific advisory panel also called for additional clinical trial data that could not be provided within the review period.

Multaq is tipped as a big earner for Sanofi and is one of 31 new medicines it hopes to file by 2010 in a bid to stave off looming patent expiries for some of its top stars, including Plavix (clopidogrel) and Lovenox (enoxaparin). And it certainly needs some good news after second-quarter financials revealed a 3.6% decline in sales and 4.4% drop in net income to 1.6 billion euros. In the same announcement, it revealed it would be stripping four products from its pipeline deemed not to have an adequate risk:benefit profile; whether this latest positive news about Multaq will help alleviate investors’ concerns over the company’s pipeline remains to be seen.