Nov. 27 (Bloomberg) -- Sanofi-Aventis SA’s most-promising experimental medicine, the Multaq heart drug, faces a March 18 hearing by a panel of Food and Drug Administration experts that will further delay approval.

The treatment, designed to treat irregular heartbeat, was granted a priority review in July, the Paris-based company said in an e-mailed statement today. The fast-track status generally means the FDA makes a decision within six months. The agency rejected Multaq once before, when it requested more clinical trials in 2006.

France’s largest drugmaker, which is replacing Chief Executive Officer Gerard le Fur next week after setbacks with the Acomplia obesity drug, needs new products to spur growth after sales fell for four consecutive quarters. The shares have gained almost 10 percent this week in anticipation Chris Viehbacher, the former GlaxoSmithKline Plc executive who takes over Dec. 1, will revive growth and speed more medicines to the market.

“The advantage with Sanofi is all the negatives are priced in and the positives aren’t,” said Michael Leacock, an analyst at Royal Bank of Scotland Group Plc in London. “The FDA seems to be doing this on a fairly routine basis. We’re fairly relaxed about it.”

Sanofi fell 58 cents, or 1.4 percent, to 41.59 euros in Paris trading. Of 34 analysts that cover the stock, 17 have “buy” ratings, while 10 recommend holding the shares and 7 advise a “sell.”

Setbacks

Multaq, Sanofi’s most-promising medicine after Acomplia failed to win the backing of U.S. regulators and side effects made it too dangerous for sale in Europe, is one of 10 drugs Sanofi says have the potential to generate more than $1 billion in annual sales, research head Marc Cluzel said at a September 2007 meeting with analysts and investors.

Sanofi had planned to introduce Multaq, one of about 30 treatments the company aimed to submit for approval by the end of 2010, in the U.S. market in the first quarter and in Europe in the third quarter of 2009.

Multaq has been plagued with delays since 2003, when Sanofi was forced to halt a study because the risk of death rose for patients taking the experimental therapy. Data from a new trial in May showed the drug reduced hospitalizations and heart-related deaths, offering a chance of approval.

The product, also known as dronedarone, treats atrial fibrillation, a condition that affects about 6.9 million patients in the U.S. and Europe. Treatment can cost about 3,000 euros ($3,876) per patient every year, Sanofi said in May. The illness can lead to shortness of breath, palpitations and fatigue.

To contact the reporter on this story: Angela Cullen in Frankfurt at acullen8@bloomberg.net

Last Updated: November 27, 2008 11:49 EST