Sanofi has suffered a setback with the news that European regulators have decided to restrict use of the firm's anti-arrhythmic Multaq.

In July, the French drugmaker discontinued the PALLAS trial in patients with permanent atrial fibrillation, different from the population with non-permanent AF for which Multaq (dronedarone) is currently approved. A significant increase in cardiovascular events was seen in the dronedarone arm, so the study was pulled. The European Medicines Agency began a safety review and its Committee for Medicinal Products for Human Use (CHMP) has now recommended restricting use.

Specifically, the CHMP says Multaq should only be prescribed for maintaining heart rhythm in patients with paroxysmal or persistent AF for the maintenance of sinus rhythm after successful cardioversion. Furthermore, it says that due to an increased risk of liver, lung and cardiovascular adverse events, Multaq should only be given after alternative treatment options have been considered and recommended a number of other risk minimisation measures.

However, the committee also noted that "the availability of a range of treatments for a difficult condition such as AF was important" and that for some patients with non-permanent AF, "Multaq remains a useful treatment option". As such, the CHMP argues that "the benefits of Multaq outweigh its risks in these patients".

It was this latter position that Sanofi stressed. Chief medical officer Jean-Pierre Lehner said the CHMP opinion is significant "as it ensures availability of an important treatment option for paroxysmal and persistent atrial fibrillation, a growing public health concern associated with life threatening consequences".

Multaq has been launched in 37 countries worldwide and been prescribed to over 440,000 patients to date. It was originally touted as a blockbuster but analysts believe that the EMA restrictions (the US Food and Drug Administration is also reviewing the drug) means that it should no longer be seen as a flagship product - in the second quarter, sales were just 68 million euros.