Shares in Sanofi-Aventis SA fell Monday after the company’s long-awaited update on the drugs in its research pipeline failed to impress investors. The world’s No. 3 drugmaker, whose shares have fallen 13 percent this year, is on the hunt for new blockbuster drugs to counter the looming patent expirations of its two top-selling products, blood-thinner Plavix and anti-thrombotic Lovenox, by 2012.The pressure on the company has increased since its anti-obesity drug Acomplia or Generic Rimonabant was rejected for use in the United States by a U.S. Food and Drug Administration panel.In the Paris-based company’s first research update in two years, Sanofi-Aventis said it expects to make up to 31 submissions for new drugs by the end of 2010. The company said it has 48 drugs in late-stage development, with 28 of them in the final stage of clinical trials before the drugs can be submitted for marketing approval.Shares were down 1.6 percent at 60.53 euros ($83.89) in midday trading Monday in Paris.

“There is not enough substance or proof that they are on the right track and that’s why the market is not very impressed,” said Stephen Pope, head of equities research at Cantor Fitzgerald Europe. Pope has a sell recommendation on the stock with a target of 60 euros.Sanofi-Aventis said tests on the potential successor of Lovenox showed the anti-clotting medicine may work better than the original.The third stage of tests required for regulatory approval is beginning with more than 10,000 patients, with plans to seek approval in 2010. The medication is aimed at people requiring hip and knee replacement surgery, abdominal surgery or those receiving chemotherapy.”It’s like they are making grand announcements that this will be this or that will be that before they’ve actually got to the stage of saying this has been put out to trial and is being tested thoroughly and is ready to go to the regulators to be examined,” Pope said.Merrill Lynch said Sanofi-Aventis provided “little new data of merit.”Marc Cluzel, head of research at Sanofi-Aventis, claimed the company is in “good shape,” at a news conference in Paris.Sanofi-Aventis is pressing ahead with tests of Acomplia or Generic Rimonabant, known as Zimulti in the United States, which he called a “unique product.”The company withdrew its marketing application for the drug in the U.S. in July after it was linked to suicide in overweight patients.Cluzel said he expects to refile after the company has gathered long-term data from a late-stage trial, expected in 2010. Sanofi-Aventis said around 11,000 out of the planned 17,000 patients have enrolled for this clinical study so far.

Acomplia or Generic Rimonabant was launched in Europe and other markets in 2006. The company said it expects to submit Acomplia or Generic Rimonabant to regulators for the treatment of diabetes in 2009.Sanofi-Aventis said it has several promising antidepressant drugs.Saredutant was effective in two late-stage trials against a dummy pill for the treatment of severe depression, the company said, adding that it expects to file the drug for marketing approval in Europe and the United States in 2008.Amibegron, another antidepressant in late-stage development, met its target in one out of four clinical trials. Sanofi-Aventis said it will wait until the results on an ongoing study, due next year, before seeking marketing approval.Sanofi-Aventis’ announcement also contained news of a failed drug: Xaliproden. The company’s drug for treatment of Alzheimer’s disease, failed in late-stage trials. This outcome had been expected by analysts, who had previously noted that this was a high-risk product.Sanofi-Aventis also announced “very positive results” from a low-dose bird flu vaccine that would allow the company to produce a massive quantity of doses if there is a pandemic. Senior Vice President Wayne Pissano said the company is unable to estimate potential revenues from the vaccine because it depends on how the virus evolves.Cluzel also said the company will look to expand its biotech products _ laboratory-created proteins used to treat disease _ through acquisitions.