Sanofi-Aventis SA is withdrawing its application to sell obesity drug rimonabant -- its biggest new drug hope -- in the United States, the French drugmaker said on Friday.

The move comes two weeks after a U.S. advisory panel said the medicine should not be approved in the world's largest drugs market because it may increase suicidal thinking and depression.

Sanofi said it would work towards resubmitting the medicine, known by the brand names Acomplia and Zimulti, at a future date and would undertake necessary discussions with the Food and Drug Administration (FDA) on required modifications to its file.

Industry analysts said the decision was a fresh setback for the hoped-for blockbuster, which is also facing an extended safety review in Europe, where it has been on the market since last year.

Paul Diggle of Nomura Code Securities said the drug might yet have a future in the United States as a niche treatment for diabetes but as a weight-loss treatment it appeared fatally wounded.

Others said the world's third-biggest drugmaker was acting proactively to save face and avoid outright rejection from the FDA.

Shaojing Tong, an analyst with Mehta Partners in New York, said the medicine could still be approved if it fares well in a large trial underway that may provide a better picture of its risks and benefits -- but this would delay approval until 2011.

This trial is longer than earlier studies and metabolic benefits from raising HDL (good) cholesterol and lowering triglycerides could be reflected in terms of patient health benefits, Tong said.

The drug is the first in a new class of drugs that switch off the same brain circuits that make people hungry when they smoke cannabis.


European regulators said they were still reviewing the latest safety data on the medicine and would only come to a final decision on the product next month.

The review is expected to be finalised at the July CHMP

(Committee for Medicinal Products for Human Use) meeting, a spokeswoman for the European Medicines Agency said.

The EU watchdog had initially said it was likely to give a view this month. Sanofi said it was submitting an update of safety data on the medicine to the CHMP.

Shares in Sanofi, which plunged on the U.S. panel decision earlier in June, gave up earlier gains to end 0.6 percent down on the day at 60.10 euros in Paris.

Acomplia is currently not recommended for European patients with major depression, due to its potential psychiatric side effects, and industry analysts believe further restrictions on its use are now very possible.

I don't think it will be withdrawn in Europe but I think the label is going to get tougher, Nomura's Diggle said. There is no way that people's forecasts are not going to come down even further.

Paris-based Sanofi has in the past trumpeted Acomplia as potential mega blockbuster, with sales of $3 billion a year or more. But actual take-up of the medicine in those markets where it is available has been slow, partly because of lack of reimbursement.

Worldwide sales of Acomplia in the first quarter of 2007 totalled just 15 million euros ($20.17 million), down from 20 million in the fourth quarter of 2006.

It is currently approved in 42 countries and marketed in 20 to treat obesity and overweight patients with associated cardiovascular risk factors.

(Additional reporting by Ransdell Pierson in New York)