Yesterday's FDA panel rejection of Sanofi's weight loss drug Acomplia could mean trouble ahead for Pfizer and Merck, which are now in Phase III testing of drugs with similar modes of action (targeting endocannabinoid receptors), The Science Daily reported yesterday. FDA data showed that Acomplia offered clinically significant weight loss results, but psychological side effects that included suicidal thoughts. Derek Lowe wrote about this in On the Pipeline earlier this week. But Acomplia's rejection has also revived rumors of a potential merger between Sanofi and BMS. PharmaTimes had the following to say this morning. "...Sanofi's hopes that rimonabant would be a blockbuster have been dashed somewhat and if any US approval of the drug, which would be called Zimulti there, does take place, it is "unlikely until the next decade at the earliest," said Bear Stearns analyst Alexandra Hauber in a research note.In another note, Paul Diggle of Nomura Code said that "if we assume the drug stays on the market outside the USA with a tougher label or is approved as a secondary product, sales won't be the $3 billion to $5 billion some people expected." He added that Zimulti was the most important product in Sanofi's pipeline, which has "relatively few growth drivers."JP Morgan downgraded the stock from 'overweight' to 'neutral', while reducing their estimates from 78 to 65 euros, noting that Sanofi is also facing the risk of generic competition for its anticoagulant Lovenox (enoxaparin), and the rumours that Total and L'Oreal are expected to dispose of their stakes in the Franco-German drugmaker will exert even more pressure on the company's share price. Sanofi's current plight has seen speculation grow that the firm may tread down the merger road and try to tie up again with Bristol-Myers Squibb. The company has underperformed its European peers by some 15% over the last year, and it still has a patent dispute over the antithrombotic blockbuster Plavix (clopidogrel) preying on its mind so long-time partner B-MS, with its reasonably healthy pipeline is looking attractive again..."