The U.S. Food and Drug Administration has notified Sanofi-Aventis that its much anticipated weight-loss drug Acomplia (rimonabant) appears to be "approvable," but will not be allowed on the market until certain unspecified conditions are met.

The news that the FDA has declined to approve Acomplia came as a severe blow to Sanofi, which had told analysts only a couple of weeks ago that it was highly confident Acomplia would be okayed by the FDA this month and would be on the market in the U.S. before the end of June.

The FDA sent the French drug maker an "approvable" letter outlining conditions that Sanofi must meet to get Acomplia approved for marketing, according to an FDA spokeswoman.

"Sanofi-Aventis will continue working in close collaboration with the FDA," the company announced on its website.

The conditions that Sanofi has to meet were not disclosed by the FDA. Spokeswoman Kathleen Quinn said: "I can confirm for you that letters were
sent but we cannot discuss any further." No Sanofi spokesperson could be reached for further comment or amplication.

A Sanofi spokeswoman told the Wall Street Journal that the company would not comment beyond the website statement, or say anything further about the FDA's communications.

On a related note, however, Sanofi also announced on its website that Acomplia -- once touted as a drug that could not only promote weight loss but also aid smoking cessation -- had been turned down by the FDA for the latter purpose.

No further details were provided, but after reporting encouraging results from a short smoking cessation trial, Sanofi never reported results on two more smoking-cessation studies. In response to an inquiry about this, a Sanofi public relations spokesperson said last month that information would be made available shortly.